/jEdit/tags/jedit-4-5-pre1/org/gjt/sp/jedit/bsh/commands/eval.bsh

/**
	Evaluate the string in the current interpreter (see source()).
	Returns the result of the evaluation or null.
	<p>

	Evaluate a string as if it were written directly in the current scope, 
	with side effects in the current scope.
	<p>
	e.g.
    <code><pre>
    a=5;
    eval("b=a*2");
    print(b); // 10
    </pre></code>
	<p>

	eval() acts just like invoked text except that any exceptions generated
	by the code are captured in a bsh.EvalError.  This includes ParseException
	for syntactic errors and TargetError for exceptions thrown by the evaluated
	code.
	<p>
	e.g.
    <pre>
    try {
        eval("foo>>><>M>JK$LJLK$");
    } catch ( EvalError e ) {
        // ParseException caught here
    }

    try {
        eval("(Integer)true");  // illegal cast
    } catch ( EvalError e ) {
        // TargetException caught here
        print( e.getTarget() )  // prints ClassCastException
    }
    </pre>
	<p>
	
	If you want eval() to throw target exceptions directly, without wrapping
	them, you can simply redefine own eval like so:

    <pre>
    myEval( String expression ) {
        try {
            return eval( expression );
        } catch ( TargetError e ) {
            throw e.getTarget();
        }
    }
    </pre>
	<p/>

	Here is a cute example of how to use eval to implement a dynamic cast.  
	i.e. to cast a script to an arbitrary type by name at run-time where the
	type is not known when you are writing the script.  In this case the type
	is in the variable interfaceType.
	<pre>
    reference = eval( "("+interfaceType+")this" );
	</pre>

	<p>
	Returns the value of the expression.
	<p>
	Throws bsh.EvalError on error
	<p>
	@return the value of the expression.
	@throws bsh.EvalError on error
*/

bsh.help.eval = "usage: eval( String expression )";

Object eval( String expression ) {
    return this.interpreter.eval( expression, this.caller.namespace );
}