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Groups > comp.lang.python > #6522

Re: scope of function parameters

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On Sonntag 29 Mai 2011, Henry Olders wrote:
> It seems that in Python, a variable inside a function is
> global unless it's assigned.

no, they are local

> I would have thought that a function parameter would
> automatically be considered local to the function. It doesn't
> make sense to me to pass a global to a function as a
> parameter.

it is local. But consider what you actually passed:
You did not pass a copy of the list but the list itself.
You could also say you passed a reference to the list.
All python variables only hold a pointer (the id) to
an object. This object has a reference count and is
automatically deleted when there are no more references
to it.

If you want a local copy of the list you can either
do what you called being ugly or do just that within
the function itself - which I think is cleaner and
only required once.

def fnc2(c):
		c = c[:]
        c[1] = 'having'
        return c


-- 
Wolfgang

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Re: scope of function parameters Wolfgang Rohdewald <wolfgang@rohdewald.de> - 2011-05-29 11:47 +0200
  Re: scope of function parameters Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-29 12:47 +0000
    Re: scope of function parameters Chris Angelico <rosuav@gmail.com> - 2011-05-30 03:53 +1000
      Re: scope of function parameters Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-29 18:28 +0000
    Re: scope of function parameters Chris Rebert <clp2@rebertia.com> - 2011-05-29 11:01 -0700
    Re: scope of function parameters Chris Angelico <rosuav@gmail.com> - 2011-05-30 04:38 +1000
      Re: scope of function parameters Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-29 18:53 +0000
        Re: scope of function parameters Chris Angelico <rosuav@gmail.com> - 2011-05-30 05:20 +1000
    Re: scope of function parameters Ian Kelly <ian.g.kelly@gmail.com> - 2011-05-29 13:12 -0600

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