On Wed, Jul 8, 2009 at 5:04 PM, derefed<dere...@gmail.com> wrote:
> How is it that the method's local variables are being remembered? My
> problem is solved by clearing the list at the end of the method, but
> I'd like to know why it acts like this is the first place.
This is a common thing encountered by new Python programmers. Python
evaluates the default values of arguments to a function or method
*once* and only once, so the empty list used initially is reused the
next time you call the method. Only the next time you call the method
it has items in it.
This applies to any mutable object used as a default value of an
argument -- lists, dictionaries, anything which can be changed and
persist the changes. As such, the way to do this in Python is
def printList(self, l=None):
if l is None:
l = []
...rest of method here...
--
"Bureaucrat Conrad, you are technically correct -- the best kind of correct."
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