bug or feature?

[Ben Sizer]

Fredrik Lundh wrote:

> it's also mentioned in chapter 4 of the tutorial:
>
>     http://docs.python.org/tut/node6.html#SECTION006710000000000000000
>
>      "*Important warning*: The default value is evaluated only once. This
>     makes a difference when the default is a mutable object such as a list,
>     dictionary, or instances of most classes. "

Perhaps it would be a good idea if Python actually raised a warning
(SyntaxWarning?) if you use an unnamed list or dict as a default
argument. This would doubtless help quite a few beginners. And for
people who really do want that behaviour, working around the warning
should involve minimal extra code, with extra clarity thrown in for
free.

-- 
Ben Sizer