Function mistaken for a method

[John Machin]

On 1/06/2006 9:46 PM, Maric Michaud wrote:
> Le Jeudi 01 Juin 2006 13:34, Peter Otten a écrit :
>> A python-coded function has a __get__ attribute, a C-function doesn't.
>> Therefore C1.f performs just the normal attribute lookup while C2.f also
>> triggers the f.__get__(C2(), C2) call via the descriptor protocol which
>> happens to return a bound method.
> I don't think it's about c-coded versus python-coded stuff, C1.f is a type, 
> C2.f is a method.
> 

Try putting f = chr (a C function); it behaves like int, not like a 
1-arg Python function. See below.

Cheers,
John

C:\junk>type func_meth.py
class C:
     f = None
     def __init__(self):
         if self.f is not None:
             self.x = self.f(0)
         else:
             self.x = 99 # differs from int(0) :-)
class C1(C):
    f = int
class C2(C):
    def f(self, arg):
         return arg != 0
class C3(C):
     pass
class C4(C):
     f = chr
for cls in (C1, C2, C3, C4):
     o = cls()
     print "callable: %r; result: %r" % (o.f, o.x)

C:\junk>func_meth.py
callable: <type 'int'>; result: 0
callable: <bound method C2.f of <__main__.C2 instance at 0x00AE6F58>>; 
result: False
callable: None; result: 99
callable: <built-in function chr>; result: '\x00'

C:\junk>