[Python-Dev] Language reference updated for metaclasses

[Mark Shannon]

Steven D'Aprano wrote:
> On Tue, Jun 05, 2012 at 10:20:58AM +0300, Eli Bendersky wrote:
> 
>> Still, instance of type()" is a bit too cryptic for mere mortals, IMHO.
> 
> I think that if somebody finds "instance of type" too cryptic, they 
> won't have any chance at all to understand metaclasses.
> 
> Personally, I think there is a lot confusing about metaclasses, but the 
> idea that classes are instances (objects) is not one of them.
> 

One thing that *is* confusing is that the metaclass parameter in class 
creation is not the metaclass (class of the class), but the class 
factory. For example:

def silly(*args):
     print(*args)
     return int

class C(metaclass=silly):
     def m(self): pass

C () {'m': <function C.m at 0xb721fe14>, '__qualname__': 'C', 
'__module__': '__main__'}

print(C)
int

In this example the metaclass (ie the class of C) is type (C is int),
even though the declared metaclass is 'silly'.

I assume it is too late to change the name of the 'metaclass' keyword to 
'factory', but we could use that terminology in the docs.

Cheers,
Mark