[Python-talk] Notes from PySIG, 28-Feb-2009

[Kent Johnson]

Lloyd Kvam wrote:
> Kent pointed out that
>         for record in Myclass.__iter__():
> will work and also provided a simple metaclass workaround.
> 
> On reflection, I think that the notion of making __iter__ a classmethod
> is a mistake.

I tend to agree that this is a bad idea, but it is possible. Here is a 
short demo of defining an __iter__() method in a metaclass so that 
direct iteration of the class object is possible. In this cas the 
construction of the actual iterator is delegated back to the class:

class MyClass(object):
     class __metaclass__(type):
         def __iter__(self):
             return MyClass._iter()

     @classmethod
     def _iter(cls):
         for i in range(4):
             yield i


for i in MyClass:
     print i


Kent