import types __docformat__ = "restructuredtext" def walk_recursive_generators(generator): """Walk a tree of generators without yielding things recursively. Let's suppose you have this: >>> def generator0(): ... yield 3 ... yield 4 ... >>> def generator1(): ... yield 2 ... for i in generator0(): ... yield i ... yield 5 ... >>> def generator2(): ... yield 1 ... for i in generator1(): ... yield i ... yield 6 ... >>> for i in generator2(): ... print i ... 1 2 3 4 5 6 Notice the way the generators are recursively yielding values. This library uses a technique called "bounce" that is usually used to implement stackless interpreters. It lets you write: >>> def generator0(): ... yield 3 ... yield 4 ... >>> def generator1(): ... yield 2 ... yield generator0() ... yield 5 ... >>> def generator2(): ... yield 1 ... yield generator1() ... yield 6 ... >>> for i in walk_recursive_generators(generator2()): ... print i ... 1 2 3 4 5 6 Look Ma! No recursive yields! """ stack = [generator] while stack: for x in stack[-1]: if isinstance(x, types.GeneratorType): stack.append(x) # Recurse. break else: yield x else: stack.pop() def _test(): import doctest doctest.testmod() if __name__ == "__main__": _test()