1 :mod:`symtable` --- Access to the compiler's symbol tables 2 ========================================================== 3 4 .. module:: symtable 5 :synopsis: Interface to the compiler's internal symbol tables. 6 7 **Source code:** :source:`Lib/symtable.py` 8 9 -------------- 10 11 .. moduleauthor:: Jeremy Hylton <jeremy (a] alum.mit.edu> 12 .. sectionauthor:: Benjamin Peterson <benjamin (a] python.org> 13 14 15 Symbol tables are generated by the compiler from AST just before bytecode is 16 generated. The symbol table is responsible for calculating the scope of every 17 identifier in the code. :mod:`symtable` provides an interface to examine these 18 tables. 19 20 21 Generating Symbol Tables 22 ------------------------ 23 24 .. function:: symtable(code, filename, compile_type) 25 26 Return the toplevel :class:`SymbolTable` for the Python source *code*. 27 *filename* is the name of the file containing the code. *compile_type* is 28 like the *mode* argument to :func:`compile`. 29 30 31 Examining Symbol Tables 32 ----------------------- 33 34 .. class:: SymbolTable 35 36 A namespace table for a block. The constructor is not public. 37 38 .. method:: get_type() 39 40 Return the type of the symbol table. Possible values are ``'class'``, 41 ``'module'``, and ``'function'``. 42 43 .. method:: get_id() 44 45 Return the table's identifier. 46 47 .. method:: get_name() 48 49 Return the table's name. This is the name of the class if the table is 50 for a class, the name of the function if the table is for a function, or 51 ``'top'`` if the table is global (:meth:`get_type` returns ``'module'``). 52 53 .. method:: get_lineno() 54 55 Return the number of the first line in the block this table represents. 56 57 .. method:: is_optimized() 58 59 Return ``True`` if the locals in this table can be optimized. 60 61 .. method:: is_nested() 62 63 Return ``True`` if the block is a nested class or function. 64 65 .. method:: has_children() 66 67 Return ``True`` if the block has nested namespaces within it. These can 68 be obtained with :meth:`get_children`. 69 70 .. method:: has_exec() 71 72 Return ``True`` if the block uses ``exec``. 73 74 .. method:: get_identifiers() 75 76 Return a list of names of symbols in this table. 77 78 .. method:: lookup(name) 79 80 Lookup *name* in the table and return a :class:`Symbol` instance. 81 82 .. method:: get_symbols() 83 84 Return a list of :class:`Symbol` instances for names in the table. 85 86 .. method:: get_children() 87 88 Return a list of the nested symbol tables. 89 90 91 .. class:: Function 92 93 A namespace for a function or method. This class inherits 94 :class:`SymbolTable`. 95 96 .. method:: get_parameters() 97 98 Return a tuple containing names of parameters to this function. 99 100 .. method:: get_locals() 101 102 Return a tuple containing names of locals in this function. 103 104 .. method:: get_globals() 105 106 Return a tuple containing names of globals in this function. 107 108 .. method:: get_frees() 109 110 Return a tuple containing names of free variables in this function. 111 112 113 .. class:: Class 114 115 A namespace of a class. This class inherits :class:`SymbolTable`. 116 117 .. method:: get_methods() 118 119 Return a tuple containing the names of methods declared in the class. 120 121 122 .. class:: Symbol 123 124 An entry in a :class:`SymbolTable` corresponding to an identifier in the 125 source. The constructor is not public. 126 127 .. method:: get_name() 128 129 Return the symbol's name. 130 131 .. method:: is_referenced() 132 133 Return ``True`` if the symbol is used in its block. 134 135 .. method:: is_imported() 136 137 Return ``True`` if the symbol is created from an import statement. 138 139 .. method:: is_parameter() 140 141 Return ``True`` if the symbol is a parameter. 142 143 .. method:: is_global() 144 145 Return ``True`` if the symbol is global. 146 147 .. method:: is_declared_global() 148 149 Return ``True`` if the symbol is declared global with a global statement. 150 151 .. method:: is_local() 152 153 Return ``True`` if the symbol is local to its block. 154 155 .. method:: is_free() 156 157 Return ``True`` if the symbol is referenced in its block, but not assigned 158 to. 159 160 .. method:: is_assigned() 161 162 Return ``True`` if the symbol is assigned to in its block. 163 164 .. method:: is_namespace() 165 166 Return ``True`` if name binding introduces new namespace. 167 168 If the name is used as the target of a function or class statement, this 169 will be true. 170 171 For example:: 172 173 >>> table = symtable.symtable("def some_func(): pass", "string", "exec") 174 >>> table.lookup("some_func").is_namespace() 175 True 176 177 Note that a single name can be bound to multiple objects. If the result 178 is ``True``, the name may also be bound to other objects, like an int or 179 list, that does not introduce a new namespace. 180 181 .. method:: get_namespaces() 182 183 Return a list of namespaces bound to this name. 184 185 .. method:: get_namespace() 186 187 Return the namespace bound to this name. If more than one namespace is 188 bound, :exc:`ValueError` is raised. 189
