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:mod:`symtable` --- Access to the compiler's symbol tables ========================================================== .. module:: symtable :synopsis: Interface to the compiler's internal symbol tables. **Source code:** :source:`Lib/symtable.py` -------------- .. moduleauthor:: Jeremy Hylton <jeremy@alum.mit.edu> .. sectionauthor:: Benjamin Peterson <benjamin@python.org> 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_star() 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_declared_global() Return ``True`` if the symbol is declared global with a global statement. .. 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. For example:: >>> table = symtable.symtable("def some_func(): pass", "string", "exec") >>> table.lookup("some_func").is_namespace() 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.