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From: Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: What is a function parameter =[] for?
Date: Wed, 18 Nov 2015 17:02:39 -0700
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On Wed, Nov 18, 2015 at 4:22 PM, Chris Angelico <rosuav@gmail.com> wrote:
> On Thu, Nov 19, 2015 at 10:14 AM, BartC <bc@freeuk.com> wrote:
>> So, looking at some source code, a default value for certain types is only
>> certain to be that value for the very first call of that function?
>
> On the contrary, it is certain always to be that exact object.

"Certain" may be a bit overly strong.

>>> def f(x=42):
...   return x
...
>>> f()
42
>>> f.__defaults__ = (43,)
>>> f()
43