On Mon, 13 Feb 2012 15:59:27 +0900, Zheng Li wrote: > how to tell a method is class method or static method or instance > method?
That's a good question, with a subtle answer that depends on exactly what you mean by the question. If you mean the object you get back from ordinary attribute access like "instance.method", then you do this: >>> class K(object): ... @classmethod ... def cmethod(cls): ... pass ... @staticmethod ... def smethod(): ... pass ... def method(self): ... pass ... >>> k = K() >>> type(k.smethod) <type 'function'> So static methods are just functions, and both class methods and instance methods share the same underlying type: >>> type(k.method) <type 'instancemethod'> >>> type(k.cmethod) <type 'instancemethod'> But if you dig deeper, you learn that all methods are actually descriptors: >>> type(K.__dict__['cmethod']) <type 'classmethod'> >>> type(K.__dict__['smethod']) <type 'staticmethod'> >>> type(K.__dict__['method']) <type 'function'> (Functions are descriptors too.) This is deep magic in Python, but if you want to learn more about it, you can read this: http://users.rcn.com/python/download/Descriptor.htm And I'll take this opportunity to plug my dualmethod descriptor: http://code.activestate.com/recipes/577030-dualmethod-descriptor/ -- Steven -- http://mail.python.org/mailman/listinfo/python-list
