Steven D'Aprano wrote:
Sometimes it seems that barely a day goes by without some newbie, or not-
so-newbie, getting confused by the behaviour of functions with mutable
default arguments. No sooner does one thread finally, and painfully, fade
away than another one starts up.
I suggest that Python should raise warnings.RuntimeWarning (or similar?)
when a function is defined with a default argument consisting of a list,
dict or set. (This is not meant as an exhaustive list of all possible
mutable types, but as the most common ones that I expect will trip up
newbies.) The warning should refer to the relevant FAQ or section in the
docs.
What do people think?
-1
People that have worked through the tutorial, something everyone should
do when they're starting out, will find this explicitly discussed. See
http://docs.python.org/tut/node6.html#SECTION006710000000000000000
People that just skim the surface get stung -- sorry.
Emile
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