Groups > comp.lang.python > #72089

Re: confused about the different built-in functions in Python

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From	Marko Rauhamaa <marko@pacujo.net>
Newsgroups	comp.lang.python
Subject	Re: confused about the different built-in functions in Python
Date	Mon, 26 May 2014 23:58:37 +0300
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Marko Rauhamaa <marko@pacujo.net>:

> Christian Heimes <christian@python.org>:
>
>> Python creates a new bound method object every time. A bound method
>> object is a callable object that keeps a strong reference to the
>> function, class and object. The bound method object adds the object as
>> first argument to the function (aka 'self').
>
> I stand corrected. I had thought the trampoline ("bound method
> object") was created once and for all.

Sure enough. The principle is explicitly specified in <URL:
https://docs.python.org/3.2/reference/datamodel.html#index-46>.

Thus:

   >>> class X:
   ...   def f(self):
   ...     print("Hello")
   ... 
   >>> x = X()
   >>> x.f()
   Hello
   >>> def f(): print("Meh")
   ... 
   >>> x.f = f
   >>> x.f()
   Meh
   >>> delattr(x, "f")
   >>> x.f()
   Hello

IOW, you can override a method with setattr() but you cannot delete a
method with delattr().


Marko

Thread

Re: confused about the different built-in functions in Python Terry Reedy <tjreedy@udel.edu> - 2014-05-26 14:51 -0400
  Re: confused about the different built-in functions in Python Marko Rauhamaa <marko@pacujo.net> - 2014-05-26 22:00 +0300
    Re: confused about the different built-in functions in Python Christian Heimes <christian@python.org> - 2014-05-26 21:47 +0200
      Re: confused about the different built-in functions in Python Marko Rauhamaa <marko@pacujo.net> - 2014-05-26 23:32 +0300
        Re: confused about the different built-in functions in Python Marko Rauhamaa <marko@pacujo.net> - 2014-05-26 23:58 +0300
          Re: confused about the different built-in functions in Python Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-05-27 11:14 +1200
          Re: confused about the different built-in functions in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-27 01:21 +0000
        Re: confused about the different built-in functions in Python Terry Reedy <tjreedy@udel.edu> - 2014-05-26 22:00 -0400

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