class variable won't icrement!

Steve Holden sholden at holdenweb.com
Thu Sep 12 17:57:00 CEST 2002


"Aahz" <aahz at pythoncraft.com> wrote in message
news:alq9hf$bn$1 at panix1.panix.com...
> In article <alpner$bm$1 at wanadoo.fr>,
> Eric Brunel  <eric.brunel at pragmadev.com> wrote:
> >
> >I always found that inheritance of class attributes to instance
attributes
> >was really misleading, and I even think it would be better if it were
> >simply removed from Python. IMHO, it would far more conform to the
> >"explicit is better than implicit" rule that is one of the basis of
Python.
>
> If I think of it as "scope resolution" rather than "inheritance", I find
> that it makes more sense.  It works exactly the same way as hiding a
> global with a local.

Well, not quite exactly the same way. If a local hides a global then there's
no way to access the global without explicit use of a namespace.

A class variable is available by instance-qualified name up until the time
the instance variable with the same name is created, which is why statements
like

    self.var += 1

can be so confusing. Especially when you compare operations that give
different results for mutable and immutable objects.

regards
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Steve Holden                                  http://www.holdenweb.com/
Python Web Programming                 http://pydish.holdenweb.com/pwp/
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