/TCL/src/commands/NamespaceCmd.cs

#undef DEBUG
/*
* NamespaceCmd.java
*
* Copyright (c) 1993-1997 Lucent Technologies.
* Copyright (c) 1997 Sun Microsystems, Inc.
* Copyright (c) 1998-1999 by Scriptics Corporation.
* Copyright (c) 1999 Moses DeJong
*
* Originally implemented by
*   Michael J. McLennan
*   Bell Labs Innovations for Lucent Technologies
*   mmclennan@lucent.com
*
* See the file "license.terms" for information on usage and
* redistribution of this file, and for a DISCLAIMER OF ALL
* WARRANTIES.
*
* Included in SQLite3 port to C# for use in testharness only;  2008 Noah B Hart
*
* RCS @(#) $Id: NamespaceCmd.java,v 1.12 2001/05/05 22:38:13 mdejong Exp $
*/
using System;
using System.Collections;
using System.Text;

namespace tcl.lang
{

  /// <summary> This class implements the built-in "namespace" command in Tcl.
  /// See the user documentation for details on what it does.
  /// </summary>


  public class NamespaceCmd : InternalRep, Command
  {

    // Flag passed to getNamespaceForQualName to indicate that it should
    // search for a namespace rather than a command or variable inside a
    // namespace. Note that this flag's value must not conflict with the values
    // of TCL.VarFlag.GLOBAL_ONLY, TCL.VarFlag.NAMESPACE_ONLY, or TCL.VarFlag.CREATE_NS_IF_UNKNOWN.


    // Initial size of stack allocated space for tail list - used when resetting
    // shadowed command references in the functin: TclResetShadowedCmdRefs.

    //private static final int NUM_TRAIL_ELEMS = 5;

    // Count of the number of namespaces created. This value is used as a
    // unique id for each namespace.

    private static long numNsCreated = 0;
    private static Object nsMutex;

    //
    // Flags used to represent the status of a namespace:
    //
    // NS_DYING -	1 means deleteNamespace has been called to delete the
    //		namespace but there are still active call frames on the Tcl
    //		stack that refer to the namespace. When the last call frame
    //		referring to it has been popped, it's variables and command
    //		will be destroyed and it will be marked "dead" (NS_DEAD).
    //		The namespace can no longer be looked up by name.
    // NS_DEAD -	1 means deleteNamespace has been called to delete the
    //		namespace and no call frames still refer to it. Its
    //		variables and command have already been destroyed. This bit
    //		allows the namespace resolution code to recognize that the
    //		namespace is "deleted". When the last namespaceName object
    //		in any byte code code unit that refers to the namespace has
    //		been freed (i.e., when the namespace's refCount is 0), the
    //		namespace's storage will be freed.

    internal const int NS_DYING = 0x01;
    internal const int NS_DEAD = 0x02;


    // Flag passed to getNamespaceForQualName to have it create all namespace
    // components of a namespace-qualified name that cannot be found. The new
    // namespaces are created within their specified parent. Note that this
    // flag's value must not conflict with the values of the flags
    // TCL.VarFlag.GLOBAL_ONLY, TCL.VarFlag.NAMESPACE_ONLY, and TCL.VarFlag.FIND_ONLY_NS

    // internal const int TCL.VarFlag.CREATE_NS_IF_UNKNOWN = 0x800;


    // This value corresponds to the Tcl_Obj.otherValuePtr pointer used
    // in the C version of Tcl 8.1. Use it to keep track of a ResolvedNsName.

    private ResolvedNsName otherValue = null;


    /*
    *----------------------------------------------------------------------
    *
    * Tcl_GetCurrentNamespace -> getCurrentNamespace
    *
    *	Returns a reference to an interpreter's currently active namespace.
    *
    * Results:
    *	Returns a reference to the interpreter's current namespace.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static Namespace getCurrentNamespace( Interp interp )
    {
      if ( interp.varFrame != null )
      {
        return interp.varFrame.ns;
      }
      else
      {
        return interp.globalNs;
      }
    }

    /*
    *----------------------------------------------------------------------
    *
    * Tcl_GetGlobalNamespace -> getGlobalNamespace
    *
    *	Returns a reference to an interpreter's global :: namespace.
    *
    * Results:
    *	Returns a reference to the specified interpreter's global namespace.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static Namespace getGlobalNamespace( Interp interp )
    {
      return interp.globalNs;
    }


    /*
    *----------------------------------------------------------------------
    *
    * Tcl_PushCallFrame -> pushCallFrame
    *
    *	Pushes a new call frame onto the interpreter's Tcl call stack.
    *	Called when executing a Tcl procedure or a "namespace eval" or
    *	"namespace inscope" command. 
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Modifies the interpreter's Tcl call stack.
    *
    *----------------------------------------------------------------------
    */

    internal static void pushCallFrame( Interp interp, CallFrame frame, Namespace namespace_Renamed, bool isProcCallFrame )
    // If true, the frame represents a
    // called Tcl procedure and may have local
    // vars. Vars will ordinarily be looked up
    // in the frame. If new variables are
    // created, they will be created in the
    // frame. If false, the frame is for a
    // "namespace eval" or "namespace inscope"
    // command and var references are treated
    // as references to namespace variables.
    {
      Namespace ns;

      if ( namespace_Renamed == null )
      {
        ns = getCurrentNamespace( interp );
      }
      else
      {
        ns = namespace_Renamed;
        if ( ( ns.flags & NS_DEAD ) != 0 )
        {
          throw new TclRuntimeError( "Trying to push call frame for dead namespace" );
        }
      }

      ns.activationCount++;
      frame.ns = ns;
      frame.isProcCallFrame = isProcCallFrame;
      frame.objv = null;

      frame.caller = interp.frame;
      frame.callerVar = interp.varFrame;

      if ( interp.varFrame != null )
      {
        frame.level = ( interp.varFrame.level + 1 );
      }
      else
      {
        frame.level = 1;
      }

      // FIXME : does Jacl need a procPtr in the CallFrame class?
      //frame.procPtr = null; 	   // no called procedure

      frame.varTable = null; // and no local variables

      // Compiled locals are not part of Jacl's CallFrame

      // Push the new call frame onto the interpreter's stack of procedure
      // call frames making it the current frame.

      interp.frame = frame;
      interp.varFrame = frame;
    }



    /*
    *----------------------------------------------------------------------
    *
    * Tcl_PopCallFrame -> popCallFrame
    *
    *	Removes a call frame from the Tcl call stack for the interpreter.
    *	Called to remove a frame previously pushed by Tcl_PushCallFrame.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *	Modifies the call stack of the interpreter. Resets various fields of
    *	the popped call frame. If a namespace has been deleted and
    *	has no more activations on the call stack, the namespace is
    *	destroyed.
    *
    *----------------------------------------------------------------------
    */

    internal static void popCallFrame( Interp interp )
    {
      CallFrame frame = interp.frame;
      int saveErrFlag;
      Namespace ns;

      // It's important to remove the call frame from the interpreter's stack
      // of call frames before deleting local variables, so that traces
      // invoked by the variable deletion don't see the partially-deleted
      // frame.

      interp.frame = frame.caller;
      interp.varFrame = frame.callerVar;

      // Delete the local variables. As a hack, we save then restore the
      // ERR_IN_PROGRESS flag in the interpreter. The problem is that there
      // could be unset traces on the variables, which cause scripts to be
      // evaluated. This will clear the ERR_IN_PROGRESS flag, losing stack
      // trace information if the procedure was exiting with an error. The
      // code below preserves the flag. Unfortunately, that isn't really
      // enough: we really should preserve the errorInfo variable too
      // (otherwise a nested error in the trace script will trash errorInfo).
      // What's really needed is a general-purpose mechanism for saving and
      // restoring interpreter state.

      saveErrFlag = ( interp.flags & Parser.ERR_IN_PROGRESS );

      if ( frame.varTable != null )
      {
        Var.deleteVars( interp, frame.varTable );
        frame.varTable = null;
      }

      interp.flags |= saveErrFlag;

      // Decrement the namespace's count of active call frames. If the
      // namespace is "dying" and there are no more active call frames,
      // call Tcl_DeleteNamespace to destroy it.

      ns = frame.ns;
      ns.activationCount--;
      if ( ( ( ns.flags & NS_DYING ) != 0 ) && ( ns.activationCount == 0 ) )
      {
        deleteNamespace( ns );
      }
      frame.ns = null;
    }

    /*
    *----------------------------------------------------------------------
    *
    * Tcl_CreateNamespace --
    *
    *	Creates a new namespace with the given name. If there is no
    *	active namespace (i.e., the interpreter is being initialized),
    *	the global :: namespace is created and returned.
    *
    * Results:
    *	Returns a reference to the new namespace if successful. If the
    *	namespace already exists or if another error occurs, this routine
    *	returns null, along with an error message in the interpreter's
    *	result object.
    *
    * Side effects:
    *	If the name contains "::" qualifiers and a parent namespace does
    *	not already exist, it is automatically created. 
    *
    *----------------------------------------------------------------------
    */

    internal static Namespace createNamespace( Interp interp, string name, DeleteProc deleteProc )
    {
      Namespace ns, ancestor;
      Namespace parent;
      Namespace globalNs = getGlobalNamespace( interp );
      string simpleName;
      StringBuilder buffer1, buffer2;

      // If there is no active namespace, the interpreter is being
      // initialized. 

      if ( ( globalNs == null ) && ( interp.varFrame == null ) )
      {
        // Treat this namespace as the global namespace, and avoid
        // looking for a parent.

        parent = null;
        simpleName = "";
      }
      else if ( name.Length == 0 )
      {
        /*
        TclObject tobj = interp.getResult();
        // FIXME : is there a test case to check this error result?
        TclString.append(tobj,
        "can't create namespace \"\": only global namespace can have empty name");
        */

        // FIXME : is there a test case to check this error result?
        interp.setResult( "can't create namespace \"\": only global namespace can have empty name" );
        return null;
      }
      else
      {
        // Find the parent for the new namespace.

        // Java does not support passing an address so we pass
        // an array of size 1 and then assign arr[0] to the value
        Namespace[] parentArr = new Namespace[1];
        Namespace[] dummyArr = new Namespace[1];
        string[] simpleArr = new string[1];

        getNamespaceForQualName( interp, name, null, ( TCL.VarFlag.CREATE_NS_IF_UNKNOWN | TCL.VarFlag.LEAVE_ERR_MSG ), parentArr, dummyArr, dummyArr, simpleArr );

        // Get the values out of the arrays!
        parent = parentArr[0];
        simpleName = simpleArr[0];


        // If the unqualified name at the end is empty, there were trailing
        // "::"s after the namespace's name which we ignore. The new
        // namespace was already (recursively) created and is referenced
        // by parent.

        if ( simpleName.Length == 0 )
        {
          return parent;
        }

        // Check for a bad namespace name and make sure that the name
        // does not already exist in the parent namespace.

        if ( parent.childTable[simpleName] != null )
        {
          /*
          TclObject tobj = interp.getResult();
          // FIXME : is there a test case to check this error result?
          TclString.append(tobj,
          "can't create namespace \"" + name + "\": already exists");
          */

          // FIXME : is there a test case to check this error result?
          interp.setResult( "can't create namespace \"" + name + "\": already exists" );
          return null;
        }
      }

      // Create the new namespace and root it in its parent. Increment the
      // count of namespaces created.

      ns = new Namespace();
      ns.name = simpleName;
      ns.fullName = null; // set below
      //ns.clientData       = clientData;
      ns.deleteProc = deleteProc;
      ns.parent = parent;
      ns.childTable = new Hashtable();
      lock ( nsMutex )
      {
        numNsCreated++;
        ns.nsId = numNsCreated;
      }
      ns.interp = interp;
      ns.flags = 0;
      ns.activationCount = 0;
      // FIXME : there was a problem with the refcount because
      // when the namespace was deleted the refocount was 0.
      // We avoid this by just using a refcount of 1 for now.
      // We can do ignore the refCount because GC will reclaim mem.
      //ns.refCount           = 0;
      ns.refCount = 1;
      ns.cmdTable = new Hashtable();
      ns.varTable = new Hashtable();
      ns.exportArray = null;
      ns.numExportPatterns = 0;
      ns.maxExportPatterns = 0;

      // Jacl does not use these tcl compiler specific members
      //ns.cmdRefEpoch        = 0;
      //ns.resolverEpoch      = 0;

      ns.resolver = null;

      if ( parent != null )
      {
        SupportClass.PutElement( parent.childTable, simpleName, ns );
      }

      // Build the fully qualified name for this namespace.

      buffer1 = new StringBuilder();
      buffer2 = new StringBuilder();
      for ( ancestor = ns; ancestor != null; ancestor = ancestor.parent )
      {
        if ( ancestor != globalNs )
        {
          buffer1.Append( "::" );
          buffer1.Append( ancestor.name );
        }
        buffer1.Append( buffer2 );

        buffer2.Length = 0;
        buffer2.Append( buffer1 );
        buffer1.Length = 0;
      }

      name = buffer2.ToString();
      ns.fullName = name;

      // Return a reference to the new namespace.

      return ns;
    }

    /*
    *----------------------------------------------------------------------
    *
    * Tcl_DeleteNamespace -> deleteNamespace
    *
    *	Deletes a namespace and all of the commands, variables, and other
    *	namespaces within it.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *	When a namespace is deleted, it is automatically removed as a
    *	child of its parent namespace. Also, all its commands, variables
    *	and child namespaces are deleted.
    *
    *----------------------------------------------------------------------
    */

    internal static void deleteNamespace( Namespace namespace_Renamed )
    {
      Namespace ns = namespace_Renamed;
      Interp interp = ns.interp;
      Namespace globalNs = getGlobalNamespace( interp );

      // If the namespace is on the call frame stack, it is marked as "dying"
      // (NS_DYING is OR'd into its flags): the namespace can't be looked up
      // by name but its commands and variables are still usable by those
      // active call frames. When all active call frames referring to the
      // namespace have been popped from the Tcl stack, popCallFrame will
      // call this procedure again to delete everything in the namespace.
      // If no nsName objects refer to the namespace (i.e., if its refCount 
      // is zero), its commands and variables are deleted and the storage for
      // its namespace structure is freed. Otherwise, if its refCount is
      // nonzero, the namespace's commands and variables are deleted but the
      // structure isn't freed. Instead, NS_DEAD is OR'd into the structure's
      // flags to allow the namespace resolution code to recognize that the
      // namespace is "deleted".

      if ( ns.activationCount > 0 )
      {
        ns.flags |= NS_DYING;
        if ( ns.parent != null )
        {
          ns.parent.childTable.Remove( ns.name );
        }
        ns.parent = null;
      }
      else
      {
        // Delete the namespace and everything in it. If this is the global
        // namespace, then clear it but don't free its storage unless the
        // interpreter is being torn down.

        teardownNamespace( ns );

        if ( ( ns != globalNs ) || ( ( interp.flags & Parser.DELETED ) != 0 ) )
        {
          // If this is the global namespace, then it may have residual
          // "errorInfo" and "errorCode" variables for errors that
          // occurred while it was being torn down.  Try to clear the
          // variable list one last time.

          Var.deleteVars( ns.interp, ns.varTable );

          ns.childTable.Clear();
          ns.cmdTable.Clear();

          // If the reference count is 0, then discard the namespace.
          // Otherwise, mark it as "dead" so that it can't be used.

          if ( ns.refCount == 0 )
          {
            free( ns );
          }
          else
          {
            ns.flags |= NS_DEAD;
          }
        }
      }
    }


    /*
    *----------------------------------------------------------------------
    *
    * TclTeardownNamespace -> teardownNamespace
    *
    *	Used internally to dismantle and unlink a namespace when it is
    *	deleted. Divorces the namespace from its parent, and deletes all
    *	commands, variables, and child namespaces.
    *
    *	This is kept separate from Tcl_DeleteNamespace so that the global
    *	namespace can be handled specially. Global variables like
    *	"errorInfo" and "errorCode" need to remain intact while other
    *	namespaces and commands are torn down, in case any errors occur.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *	Removes this namespace from its parent's child namespace hashtable.
    *	Deletes all commands, variables and namespaces in this namespace.
    *	If this is the global namespace, the "errorInfo" and "errorCode"
    *	variables are left alone and deleted later.
    *
    *----------------------------------------------------------------------
    */

    internal static void teardownNamespace( Namespace ns )
    {
      Interp interp = ns.interp;
      IEnumerator search;
      Namespace globalNs = getGlobalNamespace( interp );
      int i;

      // Start by destroying the namespace's variable table,
      // since variables might trigger traces.

      if ( ns == globalNs )
      {
        // This is the global namespace, so be careful to preserve the
        // "errorInfo" and "errorCode" variables. These might be needed
        // later on if errors occur while deleting commands. We are careful
        // to destroy and recreate the "errorInfo" and "errorCode"
        // variables, in case they had any traces on them.

        string errorInfoStr, errorCodeStr;

        try
        {

          errorInfoStr = interp.getVar( "errorInfo", TCL.VarFlag.GLOBAL_ONLY ).ToString();
        }
        catch ( TclException e )
        {
          errorInfoStr = null;
        }

        try
        {

          errorCodeStr = interp.getVar( "errorCode", TCL.VarFlag.GLOBAL_ONLY ).ToString();
        }
        catch ( TclException e )
        {
          errorCodeStr = null;
        }

        Var.deleteVars( interp, ns.varTable );

        if ( (System.Object)errorInfoStr != null )
        {
          try
          {
            interp.setVar( "errorInfo", errorInfoStr, TCL.VarFlag.GLOBAL_ONLY );
          }
          catch ( TclException e )
          {
            // ignore an exception while setting this var
          }
        }
        if ( (System.Object)errorCodeStr != null )
        {
          try
          {
            interp.setVar( "errorCode", errorCodeStr, TCL.VarFlag.GLOBAL_ONLY );
          }
          catch ( TclException e )
          {
            // ignore an exception while setting this var
          }
        }
      }
      else
      {
        // Variable table should be cleared.
        Var.deleteVars( interp, ns.varTable );
      }

      // Remove the namespace from its parent's child hashtable.

      if ( ns.parent != null )
      {
        ns.parent.childTable.Remove( ns.name );
      }
      ns.parent = null;

      // Delete all the child namespaces.
      //
      // BE CAREFUL: When each child is deleted, it will divorce
      //    itself from its parent. You can't traverse a hash table
      //    properly if its elements are being deleted. We use only
      //    the Tcl_FirstHashEntry function to be safe.

      foreach ( Namespace childNs in new ArrayList( ns.childTable.Values ) )
      {
        deleteNamespace( childNs );
      }

      // Delete all commands in this namespace. Be careful when traversing the
      // hash table: when each command is deleted, it removes itself from the
      // command table.

      // FIXME : double check that using an enumeration for a hashtable
      // that changes is ok in Java! Also call deleteCommand... correctly!
      foreach ( WrappedCommand cmd in new ArrayList( ns.cmdTable.Values ) )
      {
        interp.deleteCommandFromToken( cmd );
      }

      ns.cmdTable.Clear();

      // Free the namespace's export pattern array.

      if ( ns.exportArray != null )
      {
        ns.exportArray = null;
        ns.numExportPatterns = 0;
        ns.maxExportPatterns = 0;
      }

      // Callback invoked when namespace is deleted

      if ( ns.deleteProc != null )
      {
        ns.deleteProc.delete();
      }
      ns.deleteProc = null;

      // Reset the namespace's id field to ensure that this namespace won't
      // be interpreted as valid by, e.g., the cache validation code for
      // cached command references in Tcl_GetCommandFromObj.

      ns.nsId = 0;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceFree -> free
    *
    *	Called after a namespace has been deleted, when its
    *	reference count reaches 0.  Frees the data structure
    *	representing the namespace.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static void free( Namespace ns )
    {
      // Most of the namespace's contents are freed when the namespace is
      // deleted by Tcl_DeleteNamespace. All that remains is to free its names
      // (for error messages), and the structure itself.

      ns.name = null;
      ns.fullName = null;
    }

    /*
    *----------------------------------------------------------------------
    *
    * Tcl_Export -> exportList
    *
    *	Makes all the commands matching a pattern available to later be
    *	imported from the namespace specified by namespace (or the
    *	current namespace if namespace is null). The specified pattern is
    *	appended onto the namespace's export pattern list, which is
    *	optionally cleared beforehand.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Appends the export pattern onto the namespace's export list.
    *	Optionally reset the namespace's export pattern list.
    *
    *----------------------------------------------------------------------
    */

    internal static void exportList( Interp interp, Namespace namespace_Renamed, string pattern, bool resetListFirst )
    {
      int INIT_EXPORT_PATTERNS = 5;
      Namespace ns, exportNs;
      Namespace currNs = getCurrentNamespace( interp );
      string simplePattern, patternCpy;
      int neededElems, len, i;

      // If the specified namespace is null, use the current namespace.

      if ( namespace_Renamed == null )
      {
        ns = currNs;
      }
      else
      {
        ns = namespace_Renamed;
      }

      // If resetListFirst is true (nonzero), clear the namespace's export
      // pattern list.

      if ( resetListFirst )
      {
        if ( ns.exportArray != null )
        {
          for ( i = 0; i < ns.numExportPatterns; i++ )
          {
            ns.exportArray[i] = null;
          }
          ns.exportArray = null;
          ns.numExportPatterns = 0;
          ns.maxExportPatterns = 0;
        }
      }

      // Check that the pattern doesn't have namespace qualifiers.

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] exportNsArr = new Namespace[1];
      Namespace[] dummyArr = new Namespace[1];
      string[] simplePatternArr = new string[1];

      getNamespaceForQualName( interp, pattern, ns, TCL.VarFlag.LEAVE_ERR_MSG, exportNsArr, dummyArr, dummyArr, simplePatternArr );

      // get the values out of the arrays

      exportNs = exportNsArr[0];
      simplePattern = simplePatternArr[0];

      if ( ( exportNs != ns ) || ( pattern.CompareTo( simplePattern ) != 0 ) )
      {
        throw new TclException( interp, "invalid export pattern \"" + pattern + "\": pattern can't specify a namespace" );
      }

      // Make sure there is room in the namespace's pattern array for the
      // new pattern.

      neededElems = ns.numExportPatterns + 1;
      if ( ns.exportArray == null )
      {
        ns.exportArray = new string[INIT_EXPORT_PATTERNS];
        ns.numExportPatterns = 0;
        ns.maxExportPatterns = INIT_EXPORT_PATTERNS;
      }
      else if ( neededElems > ns.maxExportPatterns )
      {
        int numNewElems = 2 * ns.maxExportPatterns;
        string[] newArray = new string[numNewElems];
        Array.Copy( (System.Array)ns.exportArray, 0, (System.Array)newArray, 0, ns.numExportPatterns );
        ns.exportArray = newArray;
        ns.maxExportPatterns = numNewElems;
      }

      // Add the pattern to the namespace's array of export patterns.

      ns.exportArray[ns.numExportPatterns] = pattern;
      ns.numExportPatterns++;
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * Tcl_AppendExportList -> appendExportList
    *
    *	Appends onto the argument object the list of export patterns for the
    *	specified namespace.
    *
    * Results:
    *	The method will return when successful; in this case the object
    *	referenced by obj has each export pattern appended to it. If an
    *	error occurs, an exception and the interpreter's result
    *	holds an error message.
    *
    * Side effects:
    *	If necessary, the object referenced by obj is converted into
    *	a list object.
    *
    *----------------------------------------------------------------------
    */

    internal static void appendExportList( Interp interp, Namespace namespace_Renamed, TclObject obj )
    {
      Namespace ns;
      int i;

      // If the specified namespace is null, use the current namespace.

      if ( namespace_Renamed == null )
      {
        ns = getCurrentNamespace( interp );
      }
      else
      {
        ns = namespace_Renamed;
      }

      // Append the export pattern list onto objPtr.

      for ( i = 0; i < ns.numExportPatterns; i++ )
      {
        TclList.append( interp, obj, TclString.newInstance( ns.exportArray[i] ) );
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * Tcl_Import -> importList
    *
    *	Imports all of the commands matching a pattern into the namespace
    *	specified by namespace (or the current namespace if namespace
    *	is null). This is done by creating a new command (the "imported
    *	command") that points to the real command in its original namespace.
    *
    *      If matching commands are on the autoload path but haven't been
    *	loaded yet, this command forces them to be loaded, then creates
    *	the links to them.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Creates new commands in the importing namespace. These indirect
    *	calls back to the real command and are deleted if the real commands
    *	are deleted.
    *
    *----------------------------------------------------------------------
    */

    internal static void importList( Interp interp, Namespace namespace_Renamed, string pattern, bool allowOverwrite )
    {
      Namespace ns, importNs;
      Namespace currNs = getCurrentNamespace( interp );
      string simplePattern, cmdName;
      IEnumerator search;
      WrappedCommand cmd, realCmd;
      ImportRef ref_Renamed;
      WrappedCommand autoCmd, importedCmd;
      ImportedCmdData data;
      bool wasExported;
      int i, result;

      // If the specified namespace is null, use the current namespace.

      if ( namespace_Renamed == null )
      {
        ns = currNs;
      }
      else
      {
        ns = namespace_Renamed;
      }

      // First, invoke the "auto_import" command with the pattern
      // being imported.  This command is part of the Tcl library.
      // It looks for imported commands in autoloaded libraries and
      // loads them in.  That way, they will be found when we try
      // to create links below.

      autoCmd = findCommand( interp, "auto_import", null, TCL.VarFlag.GLOBAL_ONLY );

      if ( autoCmd != null )
      {
        TclObject[] objv = new TclObject[2];

        objv[0] = TclString.newInstance( "auto_import" );
        objv[0].preserve();
        objv[1] = TclString.newInstance( pattern );
        objv[1].preserve();

        cmd = autoCmd;
        try
        {
          // Invoke the command with the arguments
          cmd.cmd.cmdProc( interp, objv );
        }
        finally
        {
          objv[0].release();
          objv[1].release();
        }

        interp.resetResult();
      }

      // From the pattern, find the namespace from which we are importing
      // and get the simple pattern (no namespace qualifiers or ::'s) at
      // the end.

      if ( pattern.Length == 0 )
      {
        throw new TclException( interp, "empty import pattern" );
      }

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] importNsArr = new Namespace[1];
      Namespace[] dummyArr = new Namespace[1];
      string[] simplePatternArr = new string[1];

      getNamespaceForQualName( interp, pattern, ns, TCL.VarFlag.LEAVE_ERR_MSG, importNsArr, dummyArr, dummyArr, simplePatternArr );

      importNs = importNsArr[0];
      simplePattern = simplePatternArr[0];

      if ( importNs == null )
      {
        throw new TclException( interp, "unknown namespace in import pattern \"" + pattern + "\"" );
      }
      if ( importNs == ns )
      {
        if ( (System.Object)pattern == (System.Object)simplePattern )
        {
          throw new TclException( interp, "no namespace specified in import pattern \"" + pattern + "\"" );
        }
        else
        {
          throw new TclException( interp, "import pattern \"" + pattern + "\" tries to import from namespace \"" + importNs.name + "\" into itself" );
        }
      }

      // Scan through the command table in the source namespace and look for
      // exported commands that match the string pattern. Create an "imported
      // command" in the current namespace for each imported command; these
      // commands redirect their invocations to the "real" command.


      for ( search = importNs.cmdTable.Keys.GetEnumerator(); search.MoveNext(); )
      {

        cmdName = ( (string)search.Current );
        if ( Util.stringMatch( cmdName, simplePattern ) )
        {
          // The command cmdName in the source namespace matches the
          // pattern. Check whether it was exported. If it wasn't,
          // we ignore it.

          wasExported = false;
          for ( i = 0; i < importNs.numExportPatterns; i++ )
          {
            if ( Util.stringMatch( cmdName, importNs.exportArray[i] ) )
            {
              wasExported = true;
              break;
            }
          }
          if ( !wasExported )
          {
            continue;
          }

          // Unless there is a name clash, create an imported command
          // in the current namespace that refers to cmdPtr.

          if ( ( ns.cmdTable[cmdName] == null ) || allowOverwrite )
          {
            // Create the imported command and its client data.
            // To create the new command in the current namespace, 
            // generate a fully qualified name for it.

            StringBuilder ds;

            ds = new StringBuilder();
            ds.Append( ns.fullName );
            if ( ns != interp.globalNs )
            {
              ds.Append( "::" );
            }
            ds.Append( cmdName );

            // Check whether creating the new imported command in the
            // current namespace would create a cycle of imported->real
            // command references that also would destroy an existing
            // "real" command already in the current namespace.

            cmd = (WrappedCommand)importNs.cmdTable[cmdName];

            if ( cmd.cmd is ImportedCmdData )
            {
              // This is actually an imported command, find
              // the real command it references
              realCmd = getOriginalCommand( cmd );
              if ( ( realCmd != null ) && ( realCmd.ns == currNs ) && ( currNs.cmdTable[cmdName] != null ) )
              {
                throw new TclException( interp, "import pattern \"" + pattern + "\" would create a loop containing command \"" + ds.ToString() + "\"" );
              }
            }

            data = new ImportedCmdData();

            // Create the imported command inside the interp
            interp.createCommand( ds.ToString(), data );

            // Lookup in the namespace for the new WrappedCommand
            importedCmd = findCommand( interp, ds.ToString(), ns, ( TCL.VarFlag.NAMESPACE_ONLY | TCL.VarFlag.LEAVE_ERR_MSG ) );

            data.realCmd = cmd;
            data.self = importedCmd;

            // Create an ImportRef structure describing this new import
            // command and add it to the import ref list in the "real"
            // command.

            ref_Renamed = new ImportRef();
            ref_Renamed.importedCmd = importedCmd;
            ref_Renamed.next = cmd.importRef;
            cmd.importRef = ref_Renamed;
          }
          else
          {
            throw new TclException( interp, "can't import command \"" + cmdName + "\": already exists" );
          }
        }
      }
      return;
    }

    /*
    *----------------------------------------------------------------------
    *
    * Tcl_ForgetImport -> forgetImport
    *
    *	Deletes previously imported commands. Given a pattern that may
    *	include the name of an exporting namespace, this procedure first
    *	finds all matching exported commands. It then looks in the namespace
    *	specified by namespace for any corresponding previously imported
    *	commands, which it deletes. If namespace is null, commands are
    *	deleted from the current namespace.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	May delete commands. 
    *
    *----------------------------------------------------------------------
    */

    internal static void forgetImport( Interp interp, Namespace namespace_Renamed, string pattern )
    {
      Namespace ns, importNs, actualCtx;
      string simplePattern, cmdName;
      IEnumerator search;
      WrappedCommand cmd;

      // If the specified namespace is null, use the current namespace.

      if ( namespace_Renamed == null )
      {
        ns = getCurrentNamespace( interp );
      }
      else
      {
        ns = namespace_Renamed;
      }

      // From the pattern, find the namespace from which we are importing
      // and get the simple pattern (no namespace qualifiers or ::'s) at
      // the end.

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] importNsArr = new Namespace[1];
      Namespace[] dummyArr = new Namespace[1];
      Namespace[] actualCtxArr = new Namespace[1];
      string[] simplePatternArr = new string[1];

      getNamespaceForQualName( interp, pattern, ns, TCL.VarFlag.LEAVE_ERR_MSG, importNsArr, dummyArr, actualCtxArr, simplePatternArr );

      // get the values out of the arrays
      importNs = importNsArr[0];
      actualCtx = actualCtxArr[0];
      simplePattern = simplePatternArr[0];

      // FIXME : the above call passes TCL.VarFlag.LEAVE_ERR_MSG, but
      // it seems like this will be a problem when exception is raised!
      if ( importNs == null )
      {
        throw new TclException( interp, "unknown namespace in namespace forget pattern \"" + pattern + "\"" );
      }

      // Scan through the command table in the source namespace and look for
      // exported commands that match the string pattern. If the current
      // namespace has an imported command that refers to one of those real
      // commands, delete it.


      for ( search = importNs.cmdTable.Keys.GetEnumerator(); search.MoveNext(); )
      {

        cmdName = ( (string)search.Current );
        if ( Util.stringMatch( cmdName, simplePattern ) )
        {
          cmd = (WrappedCommand)ns.cmdTable[cmdName];
          if ( cmd != null )
          {
            // cmd of same name in current namespace
            if ( cmd.cmd is ImportedCmdData )
            {
              interp.deleteCommandFromToken( cmd );
            }
          }
        }
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * TclGetOriginalCommand -> getOriginalCommand
    *
    *	An imported command is created in a namespace when a "real" command
    *	is imported from another namespace. If the specified command is an
    *	imported command, this procedure returns the original command it
    *	refers to.
    *
    * Results:
    *	If the command was imported into a sequence of namespaces a, b,...,n
    *	where each successive namespace just imports the command from the
    *	previous namespace, this procedure returns the Tcl_Command token in
    *	the first namespace, a. Otherwise, if the specified command is not
    *	an imported command, the procedure returns null.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static WrappedCommand getOriginalCommand( WrappedCommand command )
    {
      WrappedCommand cmd = command;
      ImportedCmdData data;

      if ( !( cmd.cmd is ImportedCmdData ) )
      {
        return null;
      }

      while ( cmd.cmd is ImportedCmdData )
      {
        data = (ImportedCmdData)cmd.cmd;
        cmd = data.realCmd;
      }
      return cmd;
    }


    /*
    *----------------------------------------------------------------------
    *
    * InvokeImportedCmd -> invokeImportedCmd
    *
    *	Invoked by Tcl whenever the user calls an imported command that
    *	was created by Tcl_Import. Finds the "real" command (in another
    *	namespace), and passes control to it.
    *
    * Results:
    *	Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result object is set to an error message.
    *
    *----------------------------------------------------------------------
    */

    internal static void invokeImportedCmd( Interp interp, ImportedCmdData data, TclObject[] objv )
    {
      WrappedCommand realCmd = data.realCmd;
      realCmd.cmd.cmdProc( interp, objv );
    }


    /*
    *----------------------------------------------------------------------
    *
    * DeleteImportedCmd -> deleteImportedCmd
    *
    *	Invoked by Tcl whenever an imported command is deleted. The "real"
    *	command keeps a list of all the imported commands that refer to it,
    *	so those imported commands can be deleted when the real command is
    *	deleted. This procedure removes the imported command reference from
    *	the real command's list, and frees up the memory associated with
    *	the imported command.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *	Removes the imported command from the real command's import list.
    *
    *----------------------------------------------------------------------
    */

    internal static void deleteImportedCmd( ImportedCmdData data )
    // The data object for this imported command
    {
      WrappedCommand realCmd = data.realCmd;
      WrappedCommand self = data.self;
      ImportRef ref_Renamed, prev;

      prev = null;
      for ( ref_Renamed = realCmd.importRef; ref_Renamed != null; ref_Renamed = ref_Renamed.next )
      {
        if ( ref_Renamed.importedCmd == self )
        {
          // Remove ref from real command's list of imported commands
          // that refer to it.

          if ( prev == null )
          {
            // ref is first in list
            realCmd.importRef = ref_Renamed.next;
          }
          else
          {
            prev.next = ref_Renamed.next;
          }
          ref_Renamed = null;
          data = null;
          return;
        }
        prev = ref_Renamed;
      }

      throw new TclRuntimeError( "DeleteImportedCmd: did not find cmd in real cmd's list of import references" );
    }

    /*
    *----------------------------------------------------------------------
    *
    * TclGetNamespaceForQualName -> getNamespaceForQualName
    *
    *	Given a qualified name specifying a command, variable, or namespace,
    *	and a namespace in which to resolve the name, this procedure returns
    *	a pointer to the namespace that contains the item. A qualified name
    *	consists of the "simple" name of an item qualified by the names of
    *	an arbitrary number of containing namespace separated by "::"s. If
    *	the qualified name starts with "::", it is interpreted absolutely
    *	from the global namespace. Otherwise, it is interpreted relative to
    *	the namespace specified by cxtNsPtr if it is non-null. If cxtNsPtr
    *	is null, the name is interpreted relative to the current namespace.
    *
    *	A relative name like "foo::bar::x" can be found starting in either
    *	the current namespace or in the global namespace. So each search
    *	usually follows two tracks, and two possible namespaces are
    *	returned. If the procedure sets either nsPtrPtr[0] or altNsPtrPtr[0] to
    *	null, then that path failed.
    *
    *	If "flags" contains TCL.VarFlag.GLOBAL_ONLY, the relative qualified name is
    *	sought only in the global :: namespace. The alternate search
    *	(also) starting from the global namespace is ignored and
    *	altNsPtrPtr[0] is set null. 
    *
    *	If "flags" contains TCL.VarFlag.NAMESPACE_ONLY, the relative qualified
    *	name is sought only in the namespace specified by cxtNsPtr. The
    *	alternate search starting from the global namespace is ignored and
    *	altNsPtrPtr[0] is set null. If both TCL.VarFlag.GLOBAL_ONLY and
    *	TCL.VarFlag.NAMESPACE_ONLY are specified, TCL.VarFlag.GLOBAL_ONLY is ignored and
    *	the search starts from the namespace specified by cxtNsPtr.
    *
    *	If "flags" contains TCL.VarFlag.CREATE_NS_IF_UNKNOWN, all namespace
    *	components of the qualified name that cannot be found are
    *	automatically created within their specified parent. This makes sure
    *	that functions like Tcl_CreateCommand always succeed. There is no
    *	alternate search path, so altNsPtrPtr[0] is set null.
    *
    *	If "flags" contains TCL.VarFlag.FIND_ONLY_NS, the qualified name is treated as a
    *	reference to a namespace, and the entire qualified name is
    *	followed. If the name is relative, the namespace is looked up only
    *	in the current namespace. A pointer to the namespace is stored in
    *	nsPtrPtr[0] and null is stored in simpleNamePtr[0]. Otherwise, if
    *	TCL.VarFlag.FIND_ONLY_NS is not specified, only the leading components are
    *	treated as namespace names, and a pointer to the simple name of the
    *	final component is stored in simpleNamePtr[0].
    *
    * Results:
    *	It sets nsPtrPtr[0] and altNsPtrPtr[0] to point to the two possible
    *	namespaces which represent the last (containing) namespace in the
    *	qualified name. If the procedure sets either nsPtrPtr[0] or altNsPtrPtr[0]
    *	to null, then the search along that path failed.  The procedure also
    *	stores a pointer to the simple name of the final component in
    *	simpleNamePtr[0]. If the qualified name is "::" or was treated as a
    *	namespace reference (TCL.VarFlag.FIND_ONLY_NS), the procedure stores a pointer
    *	to the namespace in nsPtrPtr[0], null in altNsPtrPtr[0], and sets
    *	simpleNamePtr[0] to an empty string.
    *
    *	If there is an error, this procedure returns TCL_ERROR. If "flags"
    *	contains TCL_LEAVE_ERR_MSG, an error message is returned in the
    *	interpreter's result object. Otherwise, the interpreter's result
    *	object is left unchanged.
    *
    *	actualCxtPtrPtr[0] is set to the actual context namespace. It is
    *	set to the input context namespace pointer in cxtNsPtr. If cxtNsPtr
    *	is null, it is set to the current namespace context.
    *
    * Side effects:
    *	If "flags" contains TCL.VarFlag.CREATE_NS_IF_UNKNOWN, new namespaces may be
    *	created.
    *
    *----------------------------------------------------------------------
    */

    internal static void getNamespaceForQualName( Interp interp, string qualName, Namespace cxtNsPtr, TCL.VarFlag flags, Namespace[] nsPtrPtr, Namespace[] altNsPtrPtr, Namespace[] actualCxtPtrPtr, string[] simpleNamePtr )
    {


      // FIXME : remove extra method call checks when we are sure this works!

      if ( true )
      {
        // check invariants
        if ( ( nsPtrPtr == null ) || ( nsPtrPtr.Length != 1 ) )
        {

          throw new System.SystemException( "nsPtrPtr " + nsPtrPtr );
        }
        if ( ( altNsPtrPtr == null ) || ( altNsPtrPtr.Length != 1 ) )
        {

          throw new System.SystemException( "altNsPtrPtr " + altNsPtrPtr );
        }
        if ( ( actualCxtPtrPtr == null ) || ( actualCxtPtrPtr.Length != 1 ) )
        {

          throw new System.SystemException( "actualCxtPtrPtr " + actualCxtPtrPtr );
        }
        if ( ( simpleNamePtr == null ) || ( simpleNamePtr.Length != 1 ) )
        {

          throw new System.SystemException( "simpleNamePtr " + simpleNamePtr );
        }
      }




      Namespace ns = cxtNsPtr;
      Namespace altNs;
      Namespace globalNs = getGlobalNamespace( interp );
      Namespace entryNs;
      string start, end;
      string nsName;
      int len;
      int start_ind, end_ind, name_len;

      // Determine the context namespace ns in which to start the primary
      // search. If TCL.VarFlag.NAMESPACE_ONLY or TCL.VarFlag.FIND_ONLY_NS was specified, search
      // from the current namespace. If the qualName name starts with a "::"
      // or TCL.VarFlag.GLOBAL_ONLY was specified, search from the global
      // namespace. Otherwise, use the given namespace given in cxtNsPtr, or
      // if that is null, use the current namespace context. Note that we
      // always treat two or more adjacent ":"s as a namespace separator.

      if ( ( flags & ( TCL.VarFlag.NAMESPACE_ONLY | TCL.VarFlag.FIND_ONLY_NS ) ) != 0 )
      {
        ns = getCurrentNamespace( interp );
      }
      else if ( ( flags & TCL.VarFlag.GLOBAL_ONLY ) != 0 )
      {
        ns = globalNs;
      }
      else if ( ns == null )
      {
        if ( interp.varFrame != null )
        {
          ns = interp.varFrame.ns;
        }
        else
        {
          ns = interp.globalNs;
        }
      }



      start_ind = 0;
      name_len = qualName.Length;

      if ( ( name_len >= 2 ) && ( qualName[0] == ':' ) && ( qualName[1] == ':' ) )
      {
        start_ind = 2; // skip over the initial ::

        while ( ( start_ind < name_len ) && ( qualName[start_ind] == ':' ) )
        {
          start_ind++; // skip over a subsequent :
        }

        ns = globalNs;
        if ( start_ind >= name_len )
        {
          // qualName is just two or more ":"s
          nsPtrPtr[0] = globalNs;
          altNsPtrPtr[0] = null;
          actualCxtPtrPtr[0] = globalNs;
          simpleNamePtr[0] = ""; // points to empty string
          return;
        }
      }
      actualCxtPtrPtr[0] = ns;


      // Start an alternate search path starting with the global namespace.
      // However, if the starting context is the global namespace, or if the
      // flag is set to search only the namespace cxtNs, ignore the
      // alternate search path.


      altNs = globalNs;
      if ( ( ns == globalNs ) || ( ( flags & ( TCL.VarFlag.NAMESPACE_ONLY | TCL.VarFlag.FIND_ONLY_NS ) ) != 0 ) )
      {
        altNs = null;
      }


      // Loop to resolve each namespace qualifier in qualName.	

      end_ind = start_ind;

      while ( start_ind < name_len )
      {
        // Find the next namespace qualifier (i.e., a name ending in "::")
        // or the end of the qualified name  (i.e., a name ending in "\0").
        // Set len to the number of characters, starting from start,
        // in the name; set end to point after the "::"s or at the "\0".

        len = 0;
        for ( end_ind = start_ind; end_ind < name_len; end_ind++ )
        {
          if ( ( ( name_len - end_ind ) > 1 ) && ( qualName[end_ind] == ':' ) && ( qualName[end_ind + 1] == ':' ) )
          {
            end_ind += 2; // skip over the initial ::
            while ( ( end_ind < name_len ) && ( qualName[end_ind] == ':' ) )
            {
              end_ind++; // skip over a subsequent :
            }
            break;
          }
          len++;
        }


        if ( ( end_ind == name_len ) && !( ( end_ind - start_ind >= 2 ) && ( ( qualName[end_ind - 1] == ':' ) && ( qualName[end_ind - 2] == ':' ) ) ) )
        {

          // qualName ended with a simple name at start. If TCL.VarFlag.FIND_ONLY_NS
          // was specified, look this up as a namespace. Otherwise,
          // start is the name of a cmd or var and we are done.

          if ( ( flags & TCL.VarFlag.FIND_ONLY_NS ) != 0 )
          {
            // assign the string from start_ind to the end of the name string
            nsName = qualName.Substring( start_ind );
          }
          else
          {
            nsPtrPtr[0] = ns;
            altNsPtrPtr[0] = altNs;
            simpleNamePtr[0] = qualName.Substring( start_ind );
            return;
          }
        }
        else
        {
          // start points to the beginning of a namespace qualifier ending
          // in "::". Create new string with the namespace qualifier.

          nsName = qualName.Substring( start_ind, ( start_ind + len ) - ( start_ind ) );
        }



        // Look up the namespace qualifier nsName in the current namespace
        // context. If it isn't found but TCL.VarFlag.CREATE_NS_IF_UNKNOWN is set,
        // create that qualifying namespace. This is needed for procedures
        // like Tcl_CreateCommand that cannot fail.

        if ( ns != null )
        {
          entryNs = (Namespace)ns.childTable[nsName];
          if ( entryNs != null )
          {
            ns = entryNs;
          }
          else if ( ( flags & TCL.VarFlag.CREATE_NS_IF_UNKNOWN ) != 0 )
          {
            CallFrame frame = interp.newCallFrame();

            pushCallFrame( interp, frame, ns, false );
            ns = createNamespace( interp, nsName, null );

            popCallFrame( interp );
            if ( ns == null )
            {
              throw new System.SystemException( "Could not create namespace " + nsName );
            }
          }
          else
          {
            ns = null; // namespace not found and wasn't created
          }
        }


        // Look up the namespace qualifier in the alternate search path too.

        if ( altNs != null )
        {
          altNs = (Namespace)altNs.childTable[nsName];
        }

        // If both search paths have failed, return null results.

        if ( ( ns == null ) && ( altNs == null ) )
        {
          nsPtrPtr[0] = null;
          altNsPtrPtr[0] = null;
          simpleNamePtr[0] = null;
          return;
        }

        start_ind = end_ind;
      }


      // We ignore trailing "::"s in a namespace name, but in a command or
      // variable name, trailing "::"s refer to the cmd or var named {}.

      if ( ( ( flags & TCL.VarFlag.FIND_ONLY_NS ) != 0 ) || ( ( end_ind > start_ind ) && ( qualName[end_ind - 1] != ':' ) ) )
      {
        simpleNamePtr[0] = null; // found namespace name
      }
      else
      {
        // FIXME : make sure this does not throw exception when end_ind is at the end of the string 
        simpleNamePtr[0] = qualName.Substring( end_ind ); // found cmd/var: points to empty string
      }


      // As a special case, if we are looking for a namespace and qualName
      // is "" and the current active namespace (ns) is not the global
      // namespace, return null (no namespace was found). This is because
      // namespaces can not have empty names except for the global namespace.

      if ( ( ( flags & TCL.VarFlag.FIND_ONLY_NS ) != 0 ) && ( name_len == 0 ) && ( ns != globalNs ) )
      {
        ns = null;
      }

      nsPtrPtr[0] = ns;
      altNsPtrPtr[0] = altNs;
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * Tcl_FindNamespace -> findNamespace
    *
    *	Searches for a namespace.
    *
    * Results:T
    *	Returns a reference to the namespace if it is found. Otherwise,
    *	returns null and leaves an error message in the interpreter's
    *	result object if "flags" contains TCL.VarFlag.LEAVE_ERR_MSG.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static Namespace findNamespace( Interp interp, string name, Namespace contextNs, TCL.VarFlag flags )
    {
      Namespace ns;

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] nsArr = new Namespace[1];
      Namespace[] dummy1Arr = new Namespace[1];
      string[] dummy2Arr = new string[1];

      // Find the namespace(s) that contain the specified namespace name.
      // Add the TCL.VarFlag.FIND_ONLY_NS flag to resolve the name all the way down
      // to its last component, a namespace.

      getNamespaceForQualName( interp, name, contextNs, ( flags | TCL.VarFlag.FIND_ONLY_NS ), nsArr, dummy1Arr, dummy1Arr, dummy2Arr );


      // Get the values out of the arrays!
      ns = nsArr[0];

      if ( ns != null )
      {
        return ns;
      }
      else if ( ( flags & TCL.VarFlag.LEAVE_ERR_MSG ) != 0 )
      {
        /*
        interp.resetResult();
        TclString.append(interp.getResult(), "unknown namespace \"" + name + "\"");
        */

        // FIXME : is there a test case for this error?
        interp.setResult( "unknown namespace \"" + name + "\"" );
      }
      return null;
    }



    /*
    *----------------------------------------------------------------------
    *
    * Tcl_FindCommand -> findCommand
    *
    *	Searches for a command.
    *
    * Results:
    *	Returns a token for the command if it is found. Otherwise, if it
    *	can't be found or there is an error, returns null and leaves an
    *	error message in the interpreter's result object if "flags"
    *	contains TCL.VarFlag.LEAVE_ERR_MSG.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static WrappedCommand findCommand( Interp interp, string name, Namespace contextNs, TCL.VarFlag flags )
    {
      Interp.ResolverScheme res;
      Namespace cxtNs;
      Namespace[] ns = new Namespace[2];
      string simpleName;
      int search;
      //int result;
      WrappedCommand cmd;

      // If this namespace has a command resolver, then give it first
      // crack at the command resolution.  If the interpreter has any
      // command resolvers, consult them next.  The command resolver
      // procedures may return a Tcl_Command value, they may signal
      // to continue onward, or they may signal an error.

      if ( ( flags & TCL.VarFlag.GLOBAL_ONLY ) != 0 )
      {
        cxtNs = getGlobalNamespace( interp );
      }
      else if ( contextNs != null )
      {
        cxtNs = contextNs;
      }
      else
      {
        cxtNs = getCurrentNamespace( interp );
      }

      if ( cxtNs.resolver != null || interp.resolvers != null )
      {
        try
        {
          if ( cxtNs.resolver != null )
          {
            cmd = cxtNs.resolver.resolveCmd( interp, name, cxtNs, flags );
          }
          else
          {
            cmd = null;
          }

          if ( cmd == null && interp.resolvers != null )
          {
            IEnumerator enum_Renamed = interp.resolvers.GetEnumerator();
            while ( cmd == null && enum_Renamed.MoveNext() )
            {
              res = (Interp.ResolverScheme)enum_Renamed.Current;
              cmd = res.resolver.resolveCmd( interp, name, cxtNs, flags );
            }
          }

          if ( cmd != null )
          {
            return cmd;
          }
        }
        catch ( TclException e )
        {
          return null;
        }
      }

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] ns0Arr = new Namespace[1];
      Namespace[] ns1Arr = new Namespace[1];
      Namespace[] cxtNsArr = new Namespace[1];
      string[] simpleNameArr = new string[1];


      // Find the namespace(s) that contain the command.

      getNamespaceForQualName( interp, name, contextNs, flags, ns0Arr, ns1Arr, cxtNsArr, simpleNameArr );

      // Get the values out of the arrays!
      ns[0] = ns0Arr[0];
      ns[1] = ns1Arr[0];
      cxtNs = cxtNsArr[0];
      simpleName = simpleNameArr[0];



      // Look for the command in the command table of its namespace.
      // Be sure to check both possible search paths: from the specified
      // namespace context and from the global namespace.

      cmd = null;
      for ( search = 0; ( search < 2 ) && ( cmd == null ); search++ )
      {
        if ( ( ns[search] != null ) && ( (System.Object)simpleName != null ) )
        {
          cmd = (WrappedCommand)ns[search].cmdTable[simpleName];
        }
      }
      if ( cmd != null )
      {
        return cmd;
      }
      else if ( ( flags & TCL.VarFlag.LEAVE_ERR_MSG ) != 0 )
      {
        throw new TclException( interp, "unknown command \"" + name + "\"" );
      }

      return null;
    }



    /*
    *----------------------------------------------------------------------
    *
    * Tcl_FindNamespaceVar -> findNamespaceVar
    *
    *	Searches for a namespace variable, a variable not local to a
    *	procedure. The variable can be either a scalar or an array, but
    *	may not be an element of an array.
    *
    * Results:
    *	Returns a token for the variable if it is found. Otherwise, if it
    *	can't be found or there is an error, returns null and leaves an
    *	error message in the interpreter's result object if "flags"
    *	contains TCL.VarFlag.LEAVE_ERR_MSG.
    *
    * Side effects:
    *	None.
    *
    *----------------------------------------------------------------------
    */

    internal static Var findNamespaceVar( Interp interp, string name, Namespace contextNs, TCL.VarFlag flags )
    {
      Interp.ResolverScheme res;
      Namespace cxtNs;
      Namespace[] ns = new Namespace[2];
      string simpleName;
      int search;
      //int result;
      Var var;

      // If this namespace has a variable resolver, then give it first
      // crack at the variable resolution.  It may return a Tcl_Var
      // value, it may signal to continue onward, or it may signal
      // an error.

      if ( ( flags & TCL.VarFlag.GLOBAL_ONLY ) != 0 )
      {
        cxtNs = getGlobalNamespace( interp );
      }
      else if ( contextNs != null )
      {
        cxtNs = contextNs;
      }
      else
      {
        cxtNs = getCurrentNamespace( interp );
      }

      if ( cxtNs.resolver != null || interp.resolvers != null )
      {
        try
        {
          if ( cxtNs.resolver != null )
          {
            var = cxtNs.resolver.resolveVar( interp, name, cxtNs, flags );
          }
          else
          {
            var = null;
          }

          if ( var == null && interp.resolvers != null )
          {
            IEnumerator enum_Renamed = interp.resolvers.GetEnumerator();
            while ( var == null && enum_Renamed.MoveNext() )
            {
              res = (Interp.ResolverScheme)enum_Renamed.Current;
              var = res.resolver.resolveVar( interp, name, cxtNs, flags );
            }
          }

          if ( var != null )
          {
            return var;
          }
        }
        catch ( TclException e )
        {
          return null;
        }
      }

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] ns0Arr = new Namespace[1];
      Namespace[] ns1Arr = new Namespace[1];
      Namespace[] cxtNsArr = new Namespace[1];
      string[] simpleNameArr = new string[1];


      // Find the namespace(s) that contain the variable.

      getNamespaceForQualName( interp, name, contextNs, flags, ns0Arr, ns1Arr, cxtNsArr, simpleNameArr );

      // Get the values out of the arrays!
      ns[0] = ns0Arr[0];
      ns[1] = ns1Arr[0];
      cxtNs = cxtNsArr[0];
      simpleName = simpleNameArr[0];


      // Look for the variable in the variable table of its namespace.
      // Be sure to check both possible search paths: from the specified
      // namespace context and from the global namespace.

      var = null;
      for ( search = 0; ( search < 2 ) && ( var == null ); search++ )
      {
        if ( ( ns[search] != null ) && ( (System.Object)simpleName != null ) )
        {
          var = (Var)ns[search].varTable[simpleName];
        }
      }
      if ( var != null )
      {
        return var;
      }
      else if ( ( flags & TCL.VarFlag.LEAVE_ERR_MSG ) != 0 )
      {
        /*
        interp.resetResult();
        TclString.append(interp.getResult(), "unknown variable \"" + name + "\"");
        */

        // FIXME : is there a test case for this error?
        interp.setResult( "unknown variable \"" + name + "\"" );
      }
      return null;
    }

    /*
    *----------------------------------------------------------------------
    *
    * GetNamespaceFromObj -> getNamespaceFromObj
    *
    *	Returns the namespace specified by the name in a TclObject.
    *
    * Results:
    *  This method will return the Namespace object whose name
    *  is stored in the obj argument. If the namespace can't be found,
    *  a TclException is raised.
    *
    * Side effects:
    *	May update the internal representation for the object, caching the
    *	namespace reference. The next time this procedure is called, the
    *	namespace value can be found quickly.
    *
    *	If anything goes wrong, an error message is left in the
    *	interpreter's result object.
    *
    *----------------------------------------------------------------------
    */

    internal static Namespace getNamespaceFromObj( Interp interp, TclObject obj )
    {
      ResolvedNsName resName;
      Namespace ns;
      Namespace currNs = getCurrentNamespace( interp );
      int result;

      // Get the internal representation, converting to a namespace type if
      // needed. The internal representation is a ResolvedNsName that points
      // to the actual namespace.

      // FIXME : if NamespaceCmd is not the internal rep this needs to be changed!
      if ( !( obj.InternalRep is NamespaceCmd ) )
      {
        setNsNameFromAny( interp, obj );
      }
      resName = ( (NamespaceCmd)obj.InternalRep ).otherValue;

      // Check the context namespace of the resolved symbol to make sure that
      // it is fresh. If not, then force another conversion to the namespace
      // type, to discard the old rep and create a new one. Note that we
      // verify that the namespace id of the cached namespace is the same as
      // the id when we cached it; this insures that the namespace wasn't
      // deleted and a new one created at the same address.

      ns = null;
      if ( ( resName != null ) && ( resName.refNs == currNs ) && ( resName.nsId == resName.ns.nsId ) )
      {
        ns = resName.ns;
        if ( ( ns.flags & NS_DEAD ) != 0 )
        {
          ns = null;
        }
      }
      if ( ns == null )
      {
        // try again
        setNsNameFromAny( interp, obj );
        resName = ( (NamespaceCmd)obj.InternalRep ).otherValue;
        if ( resName != null )
        {
          ns = resName.ns;
          if ( ( ns.flags & NS_DEAD ) != 0 )
          {
            ns = null;
          }
        }
      }
      return ns;
    }

    /// <summary>----------------------------------------------------------------------
    /// 
    /// Tcl_SetNamespaceResolvers -> setNamespaceResolver
    /// 
    /// Sets the command/variable resolution object for a namespace,
    /// thereby changing the way that command/variable names are
    /// interpreted.  This allows extension writers to support different
    /// name resolution schemes, such as those for object-oriented
    /// packages.
    /// 
    /// Command resolution is handled by the following method:
    /// 
    /// resolveCmd (Interp interp, String name,
    /// NamespaceCmd.Namespace context, int flags)
    /// throws TclException;
    /// 
    /// Whenever a command is executed or NamespaceCmd.findCommand is invoked
    /// within the namespace, this method is called to resolve the
    /// command name.  If this method is able to resolve the name,
    /// it should return the corresponding WrappedCommand.  Otherwise,
    /// the procedure can return null, and the command will
    /// be treated under the usual name resolution rules.  Or, it can
    /// throw a TclException, and the command will be considered invalid.
    /// 
    /// Variable resolution is handled by the following method:
    /// 
    /// resolveVar (Interp interp, String name,
    /// NamespaceCmd.Namespace context, int flags)
    /// throws TclException;
    /// 
    /// If this method is able to resolve the name, it should return
    /// the variable as var object.  The method may also
    /// return null, and the variable will be treated under the usual
    /// name resolution rules.  Or, it can throw a TclException,
    /// and the variable will be considered invalid.
    /// 
    /// Results:
    /// See above.
    /// 
    /// Side effects:
    /// None.
    /// 
    /// ----------------------------------------------------------------------
    /// </summary>

    internal static void setNamespaceResolver( Namespace namespace_Renamed, Resolver resolver )
    // command and variable resolution
    {
      //  Plug in the new command resolver.

      namespace_Renamed.resolver = resolver;
    }

    /// <summary>----------------------------------------------------------------------
    /// 
    /// Tcl_GetNamespaceResolvers -> getNamespaceResolver
    /// 
    /// Returns the current command/variable resolution object
    /// for a namespace.  By default, these objects are null.
    /// New objects can be installed by calling setNamespaceResolver,
    /// to provide new name resolution rules.
    /// 
    /// Results:
    /// Returns the esolver object assigned to this namespace.
    /// Returns null otherwise.
    /// 
    /// Side effects:
    /// None.
    /// 
    /// ----------------------------------------------------------------------
    /// </summary>

    internal static Resolver getNamespaceResolver( Namespace namespace_Renamed )
    // Namespace whose resolution rules
    // are being queried.
    {
      return namespace_Renamed.resolver;
    }

    /*
    *----------------------------------------------------------------------
    *
    * Tcl_NamespaceObjCmd -> cmdProc
    *
    *	Invoked to implement the "namespace" command that creates, deletes,
    *	or manipulates Tcl namespaces. Handles the following syntax:
    *
    *	    namespace children ?name? ?pattern?
    *	    namespace code arg
    *	    namespace current
    *	    namespace delete ?name name...?
    *	    namespace eval name arg ?arg...?
    *	    namespace export ?-clear? ?pattern pattern...?
    *	    namespace forget ?pattern pattern...?
    *	    namespace import ?-force? ?pattern pattern...?
    *	    namespace inscope name arg ?arg...?
    *	    namespace origin name
    *	    namespace parent ?name?
    *	    namespace qualifiers string
    *	    namespace tail string
    *	    namespace which ?-command? ?-variable? name
    *
    * Results:
    *	Returns if the command is successful. Raises Exception if
    *	anything goes wrong.
    *
    * Side effects:
    *	Based on the subcommand name (e.g., "import"), this procedure
    *	dispatches to a corresponding member commands in this class.
    *  This method's side effects depend on whatever that subcommand does.
    *----------------------------------------------------------------------
    */

    private static readonly string[] validCmds = new string[] { "children", "code", "current", "delete", "eval", "export", "forget", "import", "inscope", "origin", "parent", "qualifiers", "tail", "which" };

    private const int OPT_CHILDREN = 0;
    private const int OPT_CODE = 1;
    private const int OPT_CURRENT = 2;
    private const int OPT_DELETE = 3;
    private const int OPT_EVAL = 4;
    private const int OPT_EXPORT = 5;
    private const int OPT_FORGET = 6;
    private const int OPT_IMPORT = 7;
    private const int OPT_INSCOPE = 8;
    private const int OPT_ORIGIN = 9;
    private const int OPT_PARENT = 10;
    private const int OPT_QUALIFIERS = 11;
    private const int OPT_TAIL = 12;
    private const int OPT_WHICH = 13;


    public TCL.CompletionCode cmdProc( Interp interp, TclObject[] objv )
    {

      int i, opt;

      if ( objv.Length < 2 )
      {
        throw new TclNumArgsException( interp, 1, objv, "subcommand ?arg ...?" );
      }

      opt = TclIndex.get( interp, objv[1], validCmds, "option", 0 );

      switch ( opt )
      {

        case OPT_CHILDREN:
          {
            childrenCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_CODE:
          {
            codeCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_CURRENT:
          {
            currentCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_DELETE:
          {
            deleteCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_EVAL:
          {
            evalCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_EXPORT:
          {
            exportCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_FORGET:
          {
            forgetCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_IMPORT:
          {
            importCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_INSCOPE:
          {
            inscopeCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_ORIGIN:
          {
            originCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_PARENT:
          {
            parentCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_QUALIFIERS:
          {
            qualifiersCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_TAIL:
          {
            tailCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }

        case OPT_WHICH:
          {
            whichCmd( interp, objv );
            return TCL.CompletionCode.RETURN;
          }
      } // end switch(opt)
      return TCL.CompletionCode.RETURN;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceChildrenCmd -> childrenCmd
    *
    *	Invoked to implement the "namespace children" command that returns a
    *	list containing the fully-qualified names of the child namespaces of
    *	a given namespace. Handles the following syntax:
    *
    *	    namespace children ?name? ?pattern?
    *
    * Results:
    *  Nothing.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */

    private static void childrenCmd( Interp interp, TclObject[] objv )
    {
      Namespace namespace_Renamed;
      Namespace ns;
      Namespace globalNs = getGlobalNamespace( interp );
      string pattern = null;
      StringBuilder buffer;
      IEnumerator search;
      TclObject list, elem;

      // Get a pointer to the specified namespace, or the current namespace.

      if ( objv.Length == 2 )
      {
        ns = getCurrentNamespace( interp );
      }
      else if ( ( objv.Length == 3 ) || ( objv.Length == 4 ) )
      {
        ns = getNamespaceFromObj( interp, objv[2] );
        if ( ns == null )
        {

          throw new TclException( interp, "unknown namespace \"" + objv[2].ToString() + "\" in namespace children command" );
        }
      }
      else
      {
        throw new TclNumArgsException( interp, 2, objv, "?name? ?pattern?" );
      }

      // Get the glob-style pattern, if any, used to narrow the search.

      buffer = new StringBuilder();
      if ( objv.Length == 4 )
      {

        string name = objv[3].ToString();

        if ( name.StartsWith( "::" ) )
        {
          pattern = name;
        }
        else
        {
          buffer.Append( ns.fullName );
          if ( ns != globalNs )
          {
            buffer.Append( "::" );
          }
          buffer.Append( name );
          pattern = buffer.ToString();
        }
      }

      // Create a list containing the full names of all child namespaces
      // whose names match the specified pattern, if any.

      list = TclList.newInstance();
      foreach ( Namespace childNs in ns.childTable.Values )
      {
        if ( ( (System.Object)pattern == null ) || Util.stringMatch( childNs.fullName, pattern ) )
        {
          elem = TclString.newInstance( childNs.fullName );
          TclList.append( interp, list, elem );
        }
      }
      interp.setResult( list );
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceCodeCmd -> codeCmd
    *
    *	Invoked to implement the "namespace code" command to capture the
    *	namespace context of a command. Handles the following syntax:
    *
    *	    namespace code arg
    *
    *	Here "arg" can be a list. "namespace code arg" produces a result
    *	equivalent to that produced by the command
    *
    *	    list namespace inscope [namespace current] $arg
    *
    *	However, if "arg" is itself a scoped value starting with
    *	"namespace inscope", then the result is just "arg".
    *
    * Results:
    *  Nothing.
    *
    * Side effects:
    *	If anything goes wrong, this procedure returns an error
    *	message as the result in the interpreter's result object.
    *
    *----------------------------------------------------------------------
    */


    private static void codeCmd( Interp interp, TclObject[] objv )
    {
      Namespace currNs;
      TclObject list, obj;
      string arg, p;
      int length;
      int p_ind;

      if ( objv.Length != 3 )
      {
        throw new TclNumArgsException( interp, 2, objv, "arg" );
      }

      // If "arg" is already a scoped value, then return it directly.


      arg = objv[2].ToString();
      length = arg.Length;

      // FIXME : we need a test for this inscope code if there is not one already!
      if ( ( length > 17 ) && ( arg[0] == 'n' ) && arg.StartsWith( "namespace" ) )
      {
        for ( p_ind = 9; ( p_ind < length ) && ( arg[p_ind] == ' ' ); p_ind++ )
        {
          // empty body: skip over spaces
        }
        if ( ( ( length - p_ind ) >= 7 ) && ( arg[p_ind] == 'i' ) && arg.Substring( p_ind ).StartsWith( "inscope" ) )
        {
          interp.setResult( objv[2] );
          return;
        }
      }

      // Otherwise, construct a scoped command by building a list with
      // "namespace inscope", the full name of the current namespace, and 
      // the argument "arg". By constructing a list, we ensure that scoped
      // commands are interpreted properly when they are executed later,
      // by the "namespace inscope" command.

      list = TclList.newInstance();
      TclList.append( interp, list, TclString.newInstance( "namespace" ) );
      TclList.append( interp, list, TclString.newInstance( "inscope" ) );

      currNs = getCurrentNamespace( interp );
      if ( currNs == getGlobalNamespace( interp ) )
      {
        obj = TclString.newInstance( "::" );
      }
      else
      {
        obj = TclString.newInstance( currNs.fullName );
      }

      TclList.append( interp, list, obj );
      TclList.append( interp, list, objv[2] );

      interp.setResult( list );
      return;
    }

    /*
    *----------------------------------------------------------------------
    *
    * NamespaceCurrentCmd -> currentCmd
    *
    *	Invoked to implement the "namespace current" command which returns
    *	the fully-qualified name of the current namespace. Handles the
    *	following syntax:
    *
    *	    namespace current
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */

    private static void currentCmd( Interp interp, TclObject[] objv )
    {

      Namespace currNs;

      if ( objv.Length != 2 )
      {
        throw new TclNumArgsException( interp, 2, objv, null );
      }

      // The "real" name of the global namespace ("::") is the null string,
      // but we return "::" for it as a convenience to programmers. Note that
      // "" and "::" are treated as synonyms by the namespace code so that it
      // is still easy to do things like:
      //
      //    namespace [namespace current]::bar { ... }

      currNs = getCurrentNamespace( interp );

      if ( currNs == getGlobalNamespace( interp ) )
      {
        // FIXME : appending to te result really screws everything up!
        // need to figure out how to disallow this!
        //TclString.append(interp.getResult(), "::");
        interp.setResult( "::" );
      }
      else
      {
        //TclString.append(interp.getResult(), currNs.fullName);
        interp.setResult( currNs.fullName );
      }
    }

    /*
    *----------------------------------------------------------------------
    *
    * NamespaceDeleteCmd -> deleteCmd
    *
    *	Invoked to implement the "namespace delete" command to delete
    *	namespace(s). Handles the following syntax:
    *
    *	    namespace delete ?name name...?
    *
    *	Each name identifies a namespace. It may include a sequence of
    *	namespace qualifiers separated by "::"s. If a namespace is found, it
    *	is deleted: all variables and procedures contained in that namespace
    *	are deleted. If that namespace is being used on the call stack, it
    *	is kept alive (but logically deleted) until it is removed from the
    *	call stack: that is, it can no longer be referenced by name but any
    *	currently executing procedure that refers to it is allowed to do so
    *	until the procedure returns. If the namespace can't be found, this
    *	procedure returns an error. If no namespaces are specified, this
    *	command does nothing.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Deletes the specified namespaces. If anything goes wrong, this
    *	procedure returns an error message in the interpreter's
    *	result object.
    *
    *----------------------------------------------------------------------
    */

    private static void deleteCmd( Interp interp, TclObject[] objv )
    {
      Namespace namespace_Renamed;
      string name;
      int i;

      if ( objv.Length < 2 )
      {
        throw new TclNumArgsException( interp, 2, objv, "?name name...?" );
      }

      // Destroying one namespace may cause another to be destroyed. Break
      // this into two passes: first check to make sure that all namespaces on
      // the command line are valid, and report any errors.

      for ( i = 2; i < objv.Length; i++ )
      {

        name = objv[i].ToString();
        namespace_Renamed = findNamespace( interp, name, null, 0 );

        if ( namespace_Renamed == null )
        {

          throw new TclException( interp, "unknown namespace \"" + objv[i].ToString() + "\" in namespace delete command" );
        }
      }

      // Okay, now delete each namespace.

      for ( i = 2; i < objv.Length; i++ )
      {

        name = objv[i].ToString();
        namespace_Renamed = findNamespace( interp, name, null, 0 );

        if ( namespace_Renamed != null )
        {
          deleteNamespace( namespace_Renamed );
        }
      }
    }

    /*
    *----------------------------------------------------------------------
    *
    * NamespaceEvalCmd -> evalCmd
    *
    *	Invoked to implement the "namespace eval" command. Executes
    *	commands in a namespace. If the namespace does not already exist,
    *	it is created. Handles the following syntax:
    *
    *	    namespace eval name arg ?arg...?
    *
    *	If more than one arg argument is specified, the command that is
    *	executed is the result of concatenating the arguments together with
    *	a space between each argument.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns the result of the command in the interpreter's result
    *	object. If anything goes wrong, this procedure returns an error
    *	message as the result.
    *
    *----------------------------------------------------------------------
    */

    private static void evalCmd( Interp interp, TclObject[] objv )
    {
      Namespace namespace_Renamed;
      CallFrame frame;
      string cmd;
      string name;
      int length;

      if ( objv.Length < 4 )
      {
        throw new TclNumArgsException( interp, 2, objv, "name arg ?arg...?" );
      }

      // Try to resolve the namespace reference, caching the result in the
      // namespace object along the way.

      namespace_Renamed = getNamespaceFromObj( interp, objv[2] );

      // If the namespace wasn't found, try to create it.

      if ( namespace_Renamed == null )
      {

        name = objv[2].ToString();
        namespace_Renamed = createNamespace( interp, name, null );
        if ( namespace_Renamed == null )
        {
          // FIXME : result hack, we get the interp result and throw it!

          throw new TclException( interp, interp.getResult().ToString() );
        }
      }

      // Make the specified namespace the current namespace and evaluate
      // the command(s).

      frame = interp.newCallFrame();
      pushCallFrame( interp, frame, namespace_Renamed, false );

      try
      {
        if ( objv.Length == 4 )
        {
          interp.eval( objv[3], 0 );
        }
        else
        {
          cmd = Util.concat( 3, objv.Length, objv );

          // eval() will delete the object when it decrements its
          // refcount after eval'ing it.

          interp.eval( cmd ); // do not pass TCL_EVAL_DIRECT, for compiler only
        }
      }
      catch ( TclException ex )
      {
        if ( ex.getCompletionCode() == TCL.CompletionCode.ERROR )
        {
          interp.addErrorInfo( "\n    (in namespace eval \"" + namespace_Renamed.fullName + "\" script line " + interp.errorLine + ")" );
        }
        throw ex;
      }
      finally
      {
        popCallFrame( interp );
      }

      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceExportCmd -> exportCmd
    *
    *	Invoked to implement the "namespace export" command that specifies
    *	which commands are exported from a namespace. The exported commands
    *	are those that can be imported into another namespace using
    *	"namespace import". Both commands defined in a namespace and
    *	commands the namespace has imported can be exported by a
    *	namespace. This command has the following syntax:
    *
    *	    namespace export ?-clear? ?pattern pattern...?
    *
    *	Each pattern may contain "string match"-style pattern matching
    *	special characters, but the pattern may not include any namespace
    *	qualifiers: that is, the pattern must specify commands in the
    *	current (exporting) namespace. The specified patterns are appended
    *	onto the namespace's list of export patterns.
    *
    *	To reset the namespace's export pattern list, specify the "-clear"
    *	flag.
    *
    *	If there are no export patterns and the "-clear" flag isn't given,
    *	this command returns the namespace's current export list.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */


    private static void exportCmd( Interp interp, TclObject[] objv )
    {
      Namespace currNs = getCurrentNamespace( interp );
      string pattern, inString;
      bool resetListFirst = false;
      int firstArg, patternCt, i;

      if ( objv.Length < 2 )
      {
        throw new TclNumArgsException( interp, 2, objv, "?-clear? ?pattern pattern...?" );
      }

      // Process the optional "-clear" argument.

      firstArg = 2;
      if ( firstArg < objv.Length )
      {

        inString = objv[firstArg].ToString();
        if ( inString.Equals( "-clear" ) )
        {
          resetListFirst = true;
          firstArg++;
        }
      }

      // If no pattern arguments are given, and "-clear" isn't specified,
      // return the namespace's current export pattern list.

      patternCt = ( objv.Length - firstArg );
      if ( patternCt == 0 )
      {
        if ( firstArg > 2 )
        {
          return;
        }
        else
        {
          // create list with export patterns
          TclObject list = TclList.newInstance();
          appendExportList( interp, currNs, list );
          interp.setResult( list );
          return;
        }
      }

      // Add each pattern to the namespace's export pattern list.

      for ( i = firstArg; i < objv.Length; i++ )
      {

        pattern = objv[i].ToString();
        exportList( interp, currNs, pattern, ( ( i == firstArg ) ? resetListFirst : false ) );
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceForgetCmd -> forgetCmd
    *
    *	Invoked to implement the "namespace forget" command to remove
    *	imported commands from a namespace. Handles the following syntax:
    *
    *	    namespace forget ?pattern pattern...?
    *
    *	Each pattern is a name like "foo::*" or "a::b::x*". That is, the
    *	pattern may include the special pattern matching characters
    *	recognized by the "string match" command, but only in the command
    *	name at the end of the qualified name; the special pattern
    *	characters may not appear in a namespace name. All of the commands
    *	that match that pattern are checked to see if they have an imported
    *	command in the current namespace that refers to the matched
    *	command. If there is an alias, it is removed.
    *	
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Imported commands are removed from the current namespace. If
    *	anything goes wrong, this procedure returns an error message in the
    *	interpreter's result object.
    *
    *----------------------------------------------------------------------
    */


    private static void forgetCmd( Interp interp, TclObject[] objv )
    {

      string pattern;
      int i;

      if ( objv.Length < 2 )
      {
        throw new TclNumArgsException( interp, 2, objv, "?pattern pattern...?" );
      }

      for ( i = 2; i < objv.Length; i++ )
      {

        pattern = objv[i].ToString();
        forgetImport( interp, null, pattern );
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceImportCmd -> importCmd
    *
    *	Invoked to implement the "namespace import" command that imports
    *	commands into a namespace. Handles the following syntax:
    *
    *	    namespace import ?-force? ?pattern pattern...?
    *
    *	Each pattern is a namespace-qualified name like "foo::*",
    *	"a::b::x*", or "bar::p". That is, the pattern may include the
    *	special pattern matching characters recognized by the "string match"
    *	command, but only in the command name at the end of the qualified
    *	name; the special pattern characters may not appear in a namespace
    *	name. All of the commands that match the pattern and which are
    *	exported from their namespace are made accessible from the current
    *	namespace context. This is done by creating a new "imported command"
    *	in the current namespace that points to the real command in its
    *	original namespace; when the imported command is called, it invokes
    *	the real command.
    *
    *	If an imported command conflicts with an existing command, it is
    *	treated as an error. But if the "-force" option is included, then
    *	existing commands are overwritten by the imported commands.
    *	
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Adds imported commands to the current namespace. If anything goes
    *	wrong, this procedure returns an error message in the interpreter's
    *	result object.
    *
    *----------------------------------------------------------------------
    */


    private static void importCmd( Interp interp, TclObject[] objv )
    {

      bool allowOverwrite = false;
      string inString, pattern;
      int i;
      int firstArg;

      if ( objv.Length < 2 )
      {
        throw new TclNumArgsException( interp, 2, objv, "?-force? ?pattern pattern...?" );
      }

      // Skip over the optional "-force" as the first argument.

      firstArg = 2;
      if ( firstArg < objv.Length )
      {

        inString = objv[firstArg].ToString();
        if ( inString.Equals( "-force" ) )
        {
          allowOverwrite = true;
          firstArg++;
        }
      }

      // Handle the imports for each of the patterns.

      for ( i = firstArg; i < objv.Length; i++ )
      {

        pattern = objv[i].ToString();
        importList( interp, null, pattern, allowOverwrite );
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceInscopeCmd -> inscopeCmd
    *
    *	Invoked to implement the "namespace inscope" command that executes a
    *	script in the context of a particular namespace. This command is not
    *	expected to be used directly by programmers; calls to it are
    *	generated implicitly when programs use "namespace code" commands
    *	to register callback scripts. Handles the following syntax:
    *
    *	    namespace inscope name arg ?arg...?
    *
    *	The "namespace inscope" command is much like the "namespace eval"
    *	command except that it has lappend semantics and the namespace must
    *	already exist. It treats the first argument as a list, and appends
    *	any arguments after the first onto the end as proper list elements.
    *	For example,
    *
    *	    namespace inscope ::foo a b c d
    *
    *	is equivalent to
    *
    *	    namespace eval ::foo [concat a [list b c d]]
    *
    *	This lappend semantics is important because many callback scripts
    *	are actually prefixes.
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the Tcl interpreter's result object.
    *
    *----------------------------------------------------------------------
    */

    private static void inscopeCmd( Interp interp, TclObject[] objv )
    {
      Namespace namespace_Renamed;
      CallFrame frame;
      int i, result;

      if ( objv.Length < 4 )
      {
        throw new TclNumArgsException( interp, 2, objv, "name arg ?arg...?" );
      }

      // Resolve the namespace reference.

      namespace_Renamed = getNamespaceFromObj( interp, objv[2] );
      if ( namespace_Renamed == null )
      {

        throw new TclException( interp, "unknown namespace \"" + objv[2].ToString() + "\" in inscope namespace command" );
      }

      // Make the specified namespace the current namespace.

      frame = interp.newCallFrame();
      pushCallFrame( interp, frame, namespace_Renamed, false );


      // Execute the command. If there is just one argument, just treat it as
      // a script and evaluate it. Otherwise, create a list from the arguments
      // after the first one, then concatenate the first argument and the list
      // of extra arguments to form the command to evaluate.

      try
      {
        if ( objv.Length == 4 )
        {
          interp.eval( objv[3], 0 );
        }
        else
        {
          TclObject[] concatObjv = new TclObject[2];
          TclObject list;
          string cmd;

          list = TclList.newInstance();
          for ( i = 4; i < objv.Length; i++ )
          {
            try
            {
              TclList.append( interp, list, objv[i] );
            }
            catch ( TclException ex )
            {
              list.release(); // free unneeded obj
              throw ex;
            }
          }

          concatObjv[0] = objv[3];
          concatObjv[1] = list;
          cmd = Util.concat( 0, 1, concatObjv );
          interp.eval( cmd ); // do not pass TCL_EVAL_DIRECT, for compiler only
          list.release(); // we're done with the list object
        }
      }
      catch ( TclException ex )
      {
        if ( ex.getCompletionCode() == TCL.CompletionCode.ERROR )
        {
          interp.addErrorInfo( "\n    (in namespace inscope \"" + namespace_Renamed.fullName + "\" script line " + interp.errorLine + ")" );
        }
        throw ex;
      }
      finally
      {
        popCallFrame( interp );
      }

      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceOriginCmd -> originCmd
    *
    *	Invoked to implement the "namespace origin" command to return the
    *	fully-qualified name of the "real" command to which the specified
    *	"imported command" refers. Handles the following syntax:
    *
    *	    namespace origin name
    *
    * Results:
    *	An imported command is created in an namespace when that namespace
    *	imports a command from another namespace. If a command is imported
    *	into a sequence of namespaces a, b,...,n where each successive
    *	namespace just imports the command from the previous namespace, this
    *	command returns the fully-qualified name of the original command in
    *	the first namespace, a. If "name" does not refer to an alias, its
    *	fully-qualified name is returned. The returned name is stored in the
    *	interpreter's result object. This procedure returns TCL_OK if
    *	successful, and TCL_ERROR if anything goes wrong.
    *
    * Side effects:
    *	If anything goes wrong, this procedure returns an error message in
    *	the interpreter's result object.
    *
    *----------------------------------------------------------------------
    */

    private static void originCmd( Interp interp, TclObject[] objv )
    {
      WrappedCommand command, origCommand;

      if ( objv.Length != 3 )
      {
        throw new TclNumArgsException( interp, 2, objv, "name" );
      }

      // FIXME : is this the right way to search for a command?

      //command = Tcl_GetCommandFromObj(interp, objv[2]);

      command = NamespaceCmd.findCommand( interp, objv[2].ToString(), null, 0 );

      if ( command == null )
      {

        throw new TclException( interp, "invalid command name \"" + objv[2].ToString() + "\"" );
      }

      origCommand = getOriginalCommand( command );
      if ( origCommand == null )
      {
        // The specified command isn't an imported command. Return the
        // command's name qualified by the full name of the namespace it
        // was defined in.

        interp.setResult( interp.getCommandFullName( command ) );
      }
      else
      {
        interp.setResult( interp.getCommandFullName( origCommand ) );
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceParentCmd -> parentCmd
    *
    *	Invoked to implement the "namespace parent" command that returns the
    *	fully-qualified name of the parent namespace for a specified
    *	namespace. Handles the following syntax:
    *
    *	    namespace parent ?name?
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */

    private static void parentCmd( Interp interp, TclObject[] objv )
    {
      Namespace ns;

      if ( objv.Length == 2 )
      {
        ns = getCurrentNamespace( interp );
      }
      else if ( objv.Length == 3 )
      {
        ns = getNamespaceFromObj( interp, objv[2] );
        if ( ns == null )
        {

          throw new TclException( interp, "unknown namespace \"" + objv[2].ToString() + "\" in namespace parent command" );
        }
      }
      else
      {
        throw new TclNumArgsException( interp, 2, objv, "?name?" );
      }

      // Report the parent of the specified namespace.

      if ( ns.parent != null )
      {
        interp.setResult( ns.parent.fullName );
      }
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceQualifiersCmd -> qualifiersCmd
    *
    *	Invoked to implement the "namespace qualifiers" command that returns
    *	any leading namespace qualifiers in a string. These qualifiers are
    *	namespace names separated by "::"s. For example, for "::foo::p" this
    *	command returns "::foo", and for "::" it returns "". This command
    *	is the complement of the "namespace tail" command. Note that this
    *	command does not check whether the "namespace" names are, in fact,
    *	the names of currently defined namespaces. Handles the following
    *	syntax:
    *
    *	    namespace qualifiers string
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */

    private static void qualifiersCmd( Interp interp, TclObject[] objv )
    {
      string name;
      int p;

      if ( objv.Length != 3 )
      {
        throw new TclNumArgsException( interp, 2, objv, "string" );
      }

      // Find the end of the string, then work backward and find
      // the start of the last "::" qualifier.


      name = objv[2].ToString();
      p = name.Length;

      while ( --p >= 0 )
      {
        if ( ( name[p] == ':' ) && ( p > 0 ) && ( name[p - 1] == ':' ) )
        {
          p -= 2; // back up over the ::
          while ( ( p >= 0 ) && ( name[p] == ':' ) )
          {
            p--; // back up over the preceeding :
          }
          break;
        }
      }

      if ( p >= 0 )
      {
        interp.setResult( name.Substring( 0, ( p + 1 ) - ( 0 ) ) );
      }
      // When no result is set the empty string is the result
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceTailCmd -> tailCmd
    *
    *	Invoked to implement the "namespace tail" command that returns the
    *	trailing name at the end of a string with "::" namespace
    *	qualifiers. These qualifiers are namespace names separated by
    *	"::"s. For example, for "::foo::p" this command returns "p", and for
    *	"::" it returns "". This command is the complement of the "namespace
    *	qualifiers" command. Note that this command does not check whether
    *	the "namespace" names are, in fact, the names of currently defined
    *	namespaces. Handles the following syntax:
    *
    *	    namespace tail string
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */


    private static void tailCmd( Interp interp, TclObject[] objv )
    {
      string name;
      int p;

      if ( objv.Length != 3 )
      {
        throw new TclNumArgsException( interp, 2, objv, "string" );
      }

      // Find the end of the string, then work backward and find the
      // last "::" qualifier.


      name = objv[2].ToString();
      p = name.Length;

      while ( --p > 0 )
      {
        if ( ( name[p] == ':' ) && ( name[p - 1] == ':' ) )
        {
          p++; // just after the last "::"
          break;
        }
      }

      if ( p >= 0 )
      {
        interp.setResult( name.Substring( p ) );
      }
      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * NamespaceWhichCmd -> whichCmd
    *
    *	Invoked to implement the "namespace which" command that returns the
    *	fully-qualified name of a command or variable. If the specified
    *	command or variable does not exist, it returns "". Handles the
    *	following syntax:
    *
    *	    namespace which ?-command? ?-variable? name
    *
    * Results:
    *  Returns if successful, raises TclException if something goes wrong.
    *
    * Side effects:
    *	Returns a result in the interpreter's result object. If anything
    *	goes wrong, the result is an error message.
    *
    *----------------------------------------------------------------------
    */


    private static void whichCmd( Interp interp, TclObject[] objv )
    {
      string arg;
      WrappedCommand cmd;
      Var variable;
      int argIndex, lookup;

      if ( objv.Length < 3 )
      {
        throw new TclNumArgsException( interp, 2, objv, "?-command? ?-variable? name" );
      }

      // Look for a flag controlling the lookup.

      argIndex = 2;
      lookup = 0; // assume command lookup by default

      arg = objv[2].ToString();
      if ( ( arg.Length > 1 ) && ( arg[0] == '-' ) )
      {
        if ( arg.Equals( "-command" ) )
        {
          lookup = 0;
        }
        else if ( arg.Equals( "-variable" ) )
        {
          lookup = 1;
        }
        else
        {
          throw new TclNumArgsException( interp, 2, objv, "?-command? ?-variable? name" );
        }
        argIndex = 3;
      }
      if ( objv.Length != ( argIndex + 1 ) )
      {
        throw new TclNumArgsException( interp, 2, objv, "?-command? ?-variable? name" );
      }

      // FIXME : check that this implementation works!

      switch ( lookup )
      {

        case 0:

          arg = objv[argIndex].ToString();

          // FIXME : is this the right way to lookup a Command token?
          //cmd = Tcl_GetCommandFromObj(interp, objv[argIndex]);
          cmd = NamespaceCmd.findCommand( interp, arg, null, 0 );

          if ( cmd == null )
          {
            return; // cmd not found, just return (no error)
          }
          interp.setResult( interp.getCommandFullName( cmd ) );
          return;


        case 1:

          arg = objv[argIndex].ToString();
          variable = NamespaceCmd.findNamespaceVar( interp, arg, null, 0 );
          if ( variable != null )
          {
            interp.setResult( Var.getVariableFullName( interp, variable ) );
          }
          return;
      }

      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * FreeNsNameInternalRep -> dispose
    *
    *	Frees the resources associated with a object's internal
    *	representation. See src/tcljava/tcl/lang/InternalRep.java
    *
    * Results:
    *	None.
    *
    * Side effects:
    *	Decrements the ref count of any Namespace structure pointed
    *	to by the nsName's internal representation. If there are no more
    *	references to the namespace, it's structure will be freed.
    *
    *----------------------------------------------------------------------
    */

    public void dispose()
    {
      bool debug;
      System.Diagnostics.Debug.WriteLine( "dispose() called for namespace object " + ( otherValue == null ? null : otherValue.ns ) );

      ResolvedNsName resName = otherValue;
      Namespace ns;

      // Decrement the reference count of the namespace. If there are no
      // more references, free it up.

      if ( resName != null )
      {
        resName.refCount--;
        if ( resName.refCount == 0 )
        {

          // Decrement the reference count for the cached namespace.  If
          // the namespace is dead, and there are no more references to
          // it, free it.

          ns = resName.ns;
          ns.refCount--;
          if ( ( ns.refCount == 0 ) && ( ( ns.flags & NS_DEAD ) != 0 ) )
          {
            free( ns );
          }
          otherValue = null;
        }
      }
    }


    /*
    *----------------------------------------------------------------------
    *
    * DupNsNameInternalRep -> duplicate
    *
    *	Get a copy of this Object for copy-on-write
    *	operations. We just increment its useCount and return the same
    *	ReflectObject because ReflectObject's cannot be modified, so
    *	they don't need copy-on-write protections.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *  None.
    *
    *----------------------------------------------------------------------
    */

    public InternalRep duplicate()
    {
      System.Diagnostics.Debug.WriteLine( "duplicate() called for namespace object " + ( otherValue == null ? null : otherValue.ns ) );

      ResolvedNsName resName = otherValue;

      if ( resName != null )
      {
        resName.refCount++;
      }

      return this;
    }


    /*
    *----------------------------------------------------------------------
    *
    * SetNsNameFromAny -> setNsNameFromAny
    *
    *	Attempt to generate a nsName internal representation for a
    *	TclObject.
    *
    * Results:
    *	Returns if the value could be converted to a proper
    *	namespace reference. Otherwise, raises TclException.
    *
    * Side effects:
    *	If successful, the object is made a nsName object. Its internal rep
    *	is set to point to a ResolvedNsName, which contains a cached pointer
    *	to the Namespace. Reference counts are kept on both the
    *	ResolvedNsName and the Namespace, so we can keep track of their
    *	usage and free them when appropriate.
    *
    *----------------------------------------------------------------------
    */

    private static void setNsNameFromAny( Interp interp, TclObject tobj )
    {
      string name;
      Namespace ns;
      ResolvedNsName resName;

      // Java does not support passing an address so we pass
      // an array of size 1 and then assign arr[0] to the value
      Namespace[] nsArr = new Namespace[1];
      Namespace[] dummy1Arr = new Namespace[1];
      string[] dummy2Arr = new string[1];

      // Get the string representation.

      name = tobj.ToString();

      // Look for the namespace "name" in the current namespace. If there is
      // an error parsing the (possibly qualified) name, return an error.
      // If the namespace isn't found, we convert the object to an nsName
      // object with a null ResolvedNsName internal rep.

      getNamespaceForQualName( interp, name, null, TCL.VarFlag.FIND_ONLY_NS, nsArr, dummy1Arr, dummy1Arr, dummy2Arr );


      // Get the values out of the arrays!
      ns = nsArr[0];

      // If we found a namespace, then create a new ResolvedNsName structure
      // that holds a reference to it.

      if ( ns != null )
      {
        Namespace currNs = getCurrentNamespace( interp );

        ns.refCount++;
        resName = new ResolvedNsName();
        resName.ns = ns;
        resName.nsId = ns.nsId;
        resName.refNs = currNs;
        resName.refCount = 1;
      }
      else
      {
        resName = null;
      }

      // By setting the new internal rep we free up the old one.

      // FIXME : should a NamespaceCmd wrap a ResolvedNsName?
      // this is confusing because it seems like the C code uses
      // a ResolvedNsName like it is the InternalRep.

      NamespaceCmd wrap = new NamespaceCmd();
      wrap.otherValue = resName;
      tobj.InternalRep = wrap;

      return;
    }


    /*
    *----------------------------------------------------------------------
    *
    * UpdateStringOfNsName -> toString
    *
    *	Return the string representation for a nsName object.
    *  This method is called only by TclObject.toString()
    *  when TclObject.stringRep is null.
    *
    * Results:
    *	None.
    *
    * Side effects:
    *   None.
    *
    *----------------------------------------------------------------------
    */

    public override string ToString()
    {
      bool debug;

      System.Diagnostics.Debug.WriteLine( "toString() called for namespace object " + ( otherValue == null ? null : otherValue.ns ) );

      ResolvedNsName resName = otherValue;
      Namespace ns;
      string name = "";

      if ( ( resName != null ) && ( resName.nsId == resName.ns.nsId ) )
      {
        ns = resName.ns;
        if ( ( ns.flags & NS_DEAD ) != 0 )
        {
          ns = null;
        }
        if ( ns != null )
        {
          name = ns.fullName;
        }
      }

      return name;
    }


    // This interface is used to provide a callback when a namespace is deleted
    // (ported Tcl_NamespaceDeleteProc to NamespaceCmd.DeleteProc)

    internal interface DeleteProc
    {
      void delete();
    }


    // This structure contains a cached pointer to a namespace that is the
    // result of resolving the namespace's name in some other namespace. It is
    // the internal representation for a nsName object. It contains the
    // pointer along with some information that is used to check the cached
    // pointer's validity. (ported Tcl_Namespace to NamespaceCmd.Namespace)

    public class Namespace
    {
      internal string name; // The namespace's simple (unqualified)
      // name. This contains no ::'s. The name of
      // the global namespace is "" although "::"
      // is an synonym.

      internal string fullName; // The namespace's fully qualified name.
      // This starts with ::.

      internal DeleteProc deleteProc; // method to invoke when namespace is deleted

      internal Namespace parent; // reference to the namespace that contains
      // this one. null is this is the global namespace.

      internal Hashtable childTable; // Contains any child namespaces. Indexed
      // by strings; values are references to
      // Namespace objects

      internal long nsId; // Unique id for the namespace.
      internal Interp interp; // The interpreter containing this namespace.

      internal int flags; // OR-ed combination of the namespace
      // status flags NS_DYING and NS_DEAD (listed below)

      internal int activationCount; // Number of "activations" or active call
      // frames for this namespace that are on
      // the Tcl call stack. The namespace won't
      // be freed until activationCount becomes zero.

      internal int refCount; // Count of references by nsName
      // objects. The namespace can't be freed
      // until refCount becomes zero.

      internal Hashtable cmdTable; // Contains all the commands currently
      // registered in the namespace. Indexed by
      // strings; values have type (WrappedCommand).
      // Commands imported by Tcl_Import have
      // Command structures that point (via an
      // ImportedCmdRef structure) to the
      // Command structure in the source
      // namespace's command table.

      internal Hashtable varTable; // Contains all the (global) variables
      // currently in this namespace. Indexed
      // by strings; values have type (Var).

      internal string[] exportArray; // Reference to an array of string patterns
      // specifying which commands are exported.
      // A pattern may include "string match"
      // style wildcard characters to specify
      // multiple commands; however, no namespace
      // qualifiers are allowed. null if no
      // export patterns are registered.

      internal int numExportPatterns; // Number of export patterns currently
      // registered using "namespace export".

      internal int maxExportPatterns; // Mumber of export patterns for which
      // space is currently allocated.


      internal Resolver resolver;
      // If non-null, this object overrides the
      // usual command and variable resolution
      // mechanism in Tcl. This procedure is invoked
      // within findCommand and findNamespaceVar to
      // resolve all command and variable references
      // within the namespace.

      // When printing out a Namespace use the full namespace name string

      public override string ToString()
      {
        return fullName;
      }
    }


    // (ported ResolvedNsName to NamespaceCmd.ResolvedNsName)

    internal class ResolvedNsName
    {
      internal Namespace ns; // reference to namespace object
      internal long nsId; // sPtr's unique namespace id. Used to
      // verify that ns is still valid
      // (e.g., it's possible that the namespace
      // was deleted and a new one created at
      // the same address).

      internal Namespace refNs; // reference to the namespace containing the
      // reference (not the namespace that
      // contains the referenced namespace).
      internal int refCount; // Reference count: 1 for each nsName
      // object that has a pointer to this
      // ResolvedNsName structure as its internal
      // rep. This structure can be freed when
      // refCount becomes zero.
    }
    static NamespaceCmd()
    {
      nsMutex = new System.Object();
    }
  }
}