Arnaud Delobelle escreveu:
> On Mar 17, 9:31 pm, Paulo da Silva <[EMAIL PROTECTED]> wrote:
...
>> I used __new__ to
>> subclass date class but now cPickle/pickle loads
>> does not work.
>>
>> from datetime import date
>> import cPickle,string
>>
>> class MyDate(date):
>> def __new__(cls,year,month=None,day=None):
>> if type(year) is str:
>> year,month,day=map(int,string.split(year,'-'))
>> if year<100:
>> year+=2000
>> return date.__new__(cls,year,month,day)
>>
>> class C1(object):
>> def __init__(self):
>> self.x=MyDate("2007-3-15")
>>
>> def f(self):
>> print self.x
>>
>> c1=C1()
>>
>> d=cPickle.dumps(c1)
>> c2=cPickle.loads(d)
>> c2.f()
>
> I haven't tried your code but I think that you may need to define a
> __reduce__ method in your MyDate class in order to give a clue to the
> python as to how to pickle its instances. For more details see:
>
> http://docs.python.org/lib/node321.html
>
> Something like:
>
> class MyDate(date):
> ...
> def __reduce__(self):
> return type(self), (self.year, self.month, self.day)
>
> might solve your problem.
>
> HTH
>
> --
> Arnaud
>
Thanks. This works exactly the way you wrote.
Yet I am misunderstanding something. Can't pickle "see" that being
MyDate derived from date it also has to look at variables from date?
When do I need to do this? I am using pickle with a lot more complex
classes without this problem.
Thank you
Paulo
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