default arguments newbie question

[Aahz Maruch]

In article <3a5cccca.77467843 at localhost>,
Victor Muslin <victor at prodigy.net> wrote:
>
>If I want a function to print "[1]" every time it is called with no
>arguments, do I have to do something like:
>
>def f(l=None):
>  if l == None:
>    print [1]
>  else:
>    print l.append(1)

Yup.  Technically, you really want to write "if l is None", though; if
you don't actually care about it being precisely None, the common idiom
is to write "if l".

Mutable default arguments are similar in some ways to static variables in
C/C++.  They are created at compile time, not execution time.
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