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Re: confusion with decorators

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Date Fri, 1 Feb 2013 02:28:41 +1100
Subject Re: confusion with decorators
From Chris Angelico <rosuav@gmail.com>
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On Fri, Feb 1, 2013 at 12:25 AM, Jason Swails <jason.swails@gmail.com> wrote:
> On Thu, Jan 31, 2013 at 12:46 AM, Steven D'Aprano
> <steve+comp.lang.python@pearwood.info> wrote:
>>
>> On Wed, 30 Jan 2013 19:34:03 -0500, Jason Swails wrote:
>>
>> > Hello,
>> >
>> > I was having some trouble understanding decorators and inheritance and
>> > all that.  This is what I was trying to do:
>> >
>> > # untested
>> > class A(object):
>> >    def _protector_decorator(fcn):
>> >       def newfcn(self, *args, **kwargs):
>> >          return fcn(self, *args, **kwargs)
>> >       return newfcn
>>
>> Well, that surely isn't going to work, because it always decorates the
>> same function, the global "fcn".
>
>
> I don't think this is right.  fcn is a passed function (at least if it acts
> as a decorator) that is declared locally in the _protector_decorator scope.
> Since newfcn is bound in the same scope and fcn is not defined inside
> newfcn, I'm pretty sure that newfcn will just grab the fcn passed into the
> decorator.

Yet it adds a level of indirection that achieves nothing. Why not simply:
def _protector_decorator(fcn):
  return fcn

? I'm not understanding the purpose here.

ChrisA

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Thread

confusion with decorators Jason Swails <jason.swails@gmail.com> - 2013-01-30 19:34 -0500
  Re: confusion with decorators Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-01-31 05:46 +0000
    Re: confusion with decorators Jason Swails <jason.swails@gmail.com> - 2013-01-31 08:25 -0500
      Re: confusion with decorators Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-01 10:16 +1100
        Re: confusion with decorators Jason Swails <jason.swails@gmail.com> - 2013-01-31 22:13 -0500
    Re: confusion with decorators Chris Angelico <rosuav@gmail.com> - 2013-02-01 02:28 +1100
    Re: confusion with decorators Jason Swails <jason.swails@gmail.com> - 2013-01-31 11:00 -0500
    Re: confusion with decorators Jason Swails <jason.swails@gmail.com> - 2013-01-31 12:53 -0500
    Re: confusion with decorators Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-01 08:31 +1100
  Re: confusion with decorators 88888 Dihedral <dihedral88888@googlemail.com> - 2013-02-01 03:26 -0800
  Re: confusion with decorators 88888 Dihedral <dihedral88888@googlemail.com> - 2013-02-01 03:26 -0800

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