HYRY wrote:
> Why the third print stement output "'comments': [(1, 2, 3)]", I think
> it should be [].
> I am using
> Python 2.4.2 (#67, Sep 28 2005, 12:41:11) [MSC v.1310 32 bit (Intel)]
> on win32.
>
> # program
> class PicInfo:
> def __init__(self, intro="", tags="", comments=[]):
This is a FAQ - and one of the most (in)famous Python's gotchas. Default
arguments are eval'd *only once* - when the def statement is eval'd,
which is usually at import time. So using a mutable object as default
value makes this object behaving somehow like a C 'static' local
variable, ie it keeps it value from call to call.
The canonical idiom is to use None instead:
class PicInfo(object):
def __init__(self, intro="", tags="", comments=None):
self.picintro = intro
self.pictags = tags
if comments is None:
comments = []
self.comments = comments
--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in '[EMAIL PROTECTED]'.split('@')])"
--
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