[Python-3000] Unbound methods -- keep creating API?

Nick Coghlan ncoghlan at gmail.com
Tue Nov 27 11:16:59 CET 2007

Greg Ewing wrote:
> Guido van Rossum wrote:
>> They have that too. See:
>>>>> f = list.append
>>>>> g = f.__get__(a)
>>>>> g
>> <built-in method append of list object at 0x590f8>
> Hmmm. It seems that C method objects are more
> like an unbound method object that's pre-bound to a
> particular class.
> I'm concerned with built-in function objects that
> are *not* methods of anything. I'm suggesting they
> should behave the same way as a Python function when
> you put one in a class, i.e. accessing it through an
> instance creates a bound method.

I think I see what you're getting at now - adding a '__get__' method to 
the basic C function wrapper that returns self when retrieved from the 
class, and a bound instancemethod when retrieved from an instance.

To illustrate the difference between builtin functions and methods:

 >>> type(str.lower)
<type 'method_descriptor'>
 >>> '__get__' in dir(str.lower)

 >>> type(map)
<type 'builtin_function_or_method'>
 >>> '__get__' in dir(map)

This seems like an eminently sensible idea to me, and not really 
something that can be done in the 2.x series.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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