Python: Symbol table

http://eli.thegreenplace.net/2010/09/18/python-internals-symbol-tables-part-1/

In computer science, a symbol table is a data structure used by a language translator such as a compiler or interpreter, where each identifier in a program’s source code is associated with information relating to its declaration or appearance in the source, such as its type, scope level and sometimes its location.


A high-level view of the front-end of CPython is:

1. Parse source code into a parse tree
2. Transform parse tree into an Abstract Syntax Tree
3. Transform AST into a Control Flow Graph
4. Emit bytecode based on the Control Flow Graph

 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. symtable provides an interface to examine these tables.