Rolf Camps <r...@roce.be>:
> Op 07-04-16 om 00:03 schreef Marko Rauhamaa:
>> IOW, if I have this class:
>>
>> class A:
>> def f(self):
>> print("f")
>>
>> and this object:
>>
>> a = A()
>>
>> then,
>>
>> a.f
>>
>> is a function that doesn't have a self argument. That function is
>> generated on the fly, and it delegates to A.f, providing it with self
>> argument.
> a.f is not a function, A.f is a function.
> a.f is an instance method. The function is not generated on the fly,
> when the method is called, it calls the function A.f with an extra
> argument __self__ (the instance a) inserted before the argument list the
> instance method was called with.
What you call an instance method *is* a function, meaning it is bound to
a callable object that in almost no outward way differs from any other
function.
It is generated on the fly:
>>> id(a.f)
140059683793288
>>> id(a.f)
140059683793864
>>> a.f is a.f
False
You are correct that the generated function is a simple trampoline that
supplies a self argument and delegates to A.f.
Or:
When a class attribute reference (for class C, say) would yield a
class method object, it is transformed into an instance method object
whose __self__ attributes is C.
<URL: https://docs.python.org/3/reference/datamodel.html?highlight=__g
etattr__#the-standard-type-hierarchy>
So the only difference between a regular function and an instance method
object is the fact that the latter has a __self__ attribute set.
Although even that small difference can be paved over:
def g():
print("g")
g.__self__ = a
a.f = g
Marko
--
https://mail.python.org/mailman/listinfo/python-list
