/Doc/library/symtable.rst
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- :mod:`symtable` --- Access to the compiler's symbol tables
- ==========================================================
- .. module:: symtable
- :synopsis: Interface to the compiler's internal symbol tables.
- .. moduleauthor:: Jeremy Hylton <jeremy@alum.mit.edu>
- .. sectionauthor:: Benjamin Peterson
- Symbol tables are generated by the compiler from AST just before bytecode is
- generated. The symbol table is responsible for calculating the scope of every
- identifier in the code. :mod:`symtable` provides an interface to examine these
- tables.
- Generating Symbol Tables
- ------------------------
- .. function:: symtable(code, filename, compile_type)
- Return the toplevel :class:`SymbolTable` for the Python source *code*.
- *filename* is the name of the file containing the code. *compile_type* is
- like the *mode* argument to :func:`compile`.
- Examining Symbol Tables
- -----------------------
- .. class:: SymbolTable
- A namespace table for a block. The constructor is not public.
- .. method:: get_type()
- Return the type of the symbol table. Possible values are ``'class'``,
- ``'module'``, and ``'function'``.
- .. method:: get_id()
- Return the table's identifier.
- .. method:: get_name()
- Return the table's name. This is the name of the class if the table is
- for a class, the name of the function if the table is for a function, or
- ``'top'`` if the table is global (:meth:`get_type` returns ``'module'``).
- .. method:: get_lineno()
- Return the number of the first line in the block this table represents.
- .. method:: is_optimized()
- Return ``True`` if the locals in this table can be optimized.
- .. method:: is_nested()
- Return ``True`` if the block is a nested class or function.
- .. method:: has_children()
- Return ``True`` if the block has nested namespaces within it. These can
- be obtained with :meth:`get_children`.
- .. method:: has_exec()
- Return ``True`` if the block uses ``exec``.
- .. method:: has_import_start()
- Return ``True`` if the block uses a starred from-import.
- .. method:: get_identifiers()
- Return a list of names of symbols in this table.
- .. method:: lookup(name)
- Lookup *name* in the table and return a :class:`Symbol` instance.
- .. method:: get_symbols()
- Return a list of :class:`Symbol` instances for names in the table.
- .. method:: get_children()
- Return a list of the nested symbol tables.
- .. class:: Function
- A namespace for a function or method. This class inherits
- :class:`SymbolTable`.
- .. method:: get_parameters()
- Return a tuple containing names of parameters to this function.
- .. method:: get_locals()
- Return a tuple containing names of locals in this function.
- .. method:: get_globals()
- Return a tuple containing names of globals in this function.
- .. method:: get_frees()
- Return a tuple containing names of free variables in this function.
- .. class:: Class
- A namespace of a class. This class inherits :class:`SymbolTable`.
- .. method:: get_methods()
- Return a tuple containing the names of methods declared in the class.
- .. class:: Symbol
- An entry in a :class:`SymbolTable` corresponding to an identifier in the
- source. The constructor is not public.
- .. method:: get_name()
- Return the symbol's name.
- .. method:: is_referenced()
- Return ``True`` if the symbol is used in its block.
- .. method:: is_imported()
- Return ``True`` if the symbol is created from an import statement.
- .. method:: is_parameter()
- Return ``True`` if the symbol is a parameter.
- .. method:: is_global()
- Return ``True`` if the symbol is global.
- .. method:: is_local()
- Return ``True`` if the symbol is local to its block.
- .. method:: is_free()
- Return ``True`` if the symbol is referenced in its block, but not assigned
- to.
- .. method:: is_assigned()
- Return ``True`` if the symbol is assigned to in its block.
- .. method:: is_namespace()
- Return ``True`` if name binding introduces new namespace.
- If the name is used as the target of a function or class statement, this
- will be true.
- Note that a single name can be bound to multiple objects. If the result
- is ``True``, the name may also be bound to other objects, like an int or
- list, that does not introduce a new namespace.
- .. method:: get_namespaces()
- Return a list of namespaces bound to this name.
- .. method:: get_namespace()
- Return the namespace bound to this name. If more than one namespace is
- bound, a :exc:`ValueError` is raised.