Attack a sacred Python Cow

Nikolaus Rath Nikolaus at rath.org
Mon Jul 28 09:35:16 CEST 2008


Michael Torrie <torriem at gmail.com> writes:
> Colin J. Williams wrote:
>>>
>>>     def fun( ., cat):
>>>
>> I don't see the need for the comma in fun.
>
> It (the entire first variable!) is needed because a method object is
> constructed from a normal function object:
>
> def method(self,a,b):
> 	pass
>
> class MyClass(object):
> 	pass
>
> MyClass.testmethod=method
>
> That's precisely the same as if you'd defined method inside of the class
> to begin with.  A function becomes a method when the lookup procedure in
> the instance object looks up the attribute and returns (from what I
> understand) essentially a closure that binds the instance to the first
> variable of the function.  The result is known as a bound method, which
> is a callable object:
>
>>>> instance=MyClass()
>
>>>> instance.testmethod
> <bound method MyClass.testmethod of <__main__.instance object at xxx>>
>
>
> How would this work if there was not first parameter at all?
>
> In short, unlike what most of the implicit self advocates are
> saying, it's not just a simple change to the python parser to do
> this. It would require a change in the interpreter itself and how it
> deals with classes.


Thats true. But out of curiosity: why is changing the interpreter such
a bad thing? (If we suppose for now that the change itself is a good
idea).


Best,


   -Nikolaus

-- 
 »It is not worth an intelligent man's time to be in the majority.
  By definition, there are already enough people to do that.«
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