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From: Marko Rauhamaa <marko@pacujo.net>
Newsgroups: comp.lang.python
Subject: Re: Late-binding of function defaults (was Re: What is a function parameter =[] for?)
Date: Thu, 19 Nov 2015 22:57:10 +0200
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Laura Creighton <lac@openend.se>:

> My experience says that the people who are confused want lists to
> behave like tuples. period. i.e. they don't want lists to be mutable.

I think it's simpler than that. When you have:

   def f(x=[]):
       y = []

the first [] is evaluated when "def" is executed, while the latter [] is
evaluated whenever "f" is executed. It's easy to be confused.


Marko