Stackoverflow: What is a metaclass in Python?

[fanzeyi]

http://stackoverflow.com/questions/100003/what-is-a-metaclass-in-python/6581949#6581949

同时关于 Python 的修饰器的讨论：

http://stackoverflow.com/questions/739654/understanding-python-decorators/1594484#1594484

关于迭代器 yield 的讨论：

http://stackoverflow.com/questions/231767/the-python-yield-keyword-explained/231855#231855