At 12:02 PM 6/28/2006 +1200, Greg Ewing wrote:
>Martin v. Löwis wrote:
>
> > Again, I believe this is all included for ExtensionClasses: it looks
> > for __class__ on the object if the type check fails, so that an
> > ExtensionClass could be actually a class derived from the C type.
>
>Now that we
Martin v. Löwis wrote:
> Again, I believe this is all included for ExtensionClasses: it looks
> for __class__ on the object if the type check fails, so that an
> ExtensionClass could be actually a class derived from the C type.
Now that we have had new-style classes for quite a
while, is there st
At 02:49 PM 6/27/2006 +0200, Martin v. Löwis wrote:
>Phillip J. Eby wrote:
> >> It seems that the __class__ is only accessed in some cases, but not
> >> always, leading to what I think is a semantic inconsistency.
> >
> > It's not inconsistent - isinstance() checks __class__ in *addition* to
> > t
At 09:29 AM 6/27/2006 +0200, Maric Michaud wrote:
>Le mardi 27 juin 2006 05:38, Phillip J. Eby a écrit :
> > As it happens, this is due to the fact that E is a type, while E() is
> > not. There's an optimization in the isinstance() machinery that simply
> > checks to see if D().__class__ is a subt
At 10:13 PM 6/26/2006 -0700, Guido van Rossum wrote:
>On 6/26/06, Greg Ewing <[EMAIL PROTECTED]> wrote:
>>Phillip J. Eby wrote:
>>
>> > It's not inconsistent - isinstance() checks __class__ in *addition* to
>> > type() in order to allow proxying tricks like lying about your
>> > __class__.
>>
>>If
Martin Maly wrote:
> Thanks for the response. The code snippet I sent deals with new style
> classes only so I assume that in some cases isinstance falls back to
> old-style-like handling which then asks for __bases__ and __class__
> etc, possibly incorrectly so on new style classes.
Again, I beli
Phillip J. Eby wrote:
>> It seems that the __class__ is only accessed in some cases, but not
>> always, leading to what I think is a semantic inconsistency.
>
> It's not inconsistent - isinstance() checks __class__ in *addition* to
> type() in order to allow proxying tricks like lying about you
Le mardi 27 juin 2006 05:38, Phillip J. Eby a écrit :
> At 05:16 PM 6/26/2006 -0700, Martin Maly wrote:
> > >>> class D(object):
> >
> >... def getclass(self):
> >... print "D.getclass"
> >... return C
> >... __class__ = property(getclass)
> >...
> >
> > >>> isinstance(D(),
On 6/26/06, Greg Ewing <[EMAIL PROTECTED]> wrote:
> Phillip J. Eby wrote:
>
> > It's not inconsistent - isinstance() checks __class__ in *addition* to
> > type() in order to allow proxying tricks like lying about your
> > __class__.
>
> If this is a deliberate feature, it's a bit patchy, because
>
Phillip J. Eby wrote:
> It's not inconsistent - isinstance() checks __class__ in *addition* to
> type() in order to allow proxying tricks like lying about your
> __class__.
If this is a deliberate feature, it's a bit patchy, because
it means the proxy can't lie about *not* being an instance
of
At 08:04 PM 6/26/2006 -0700, Martin Maly wrote:
>Thanks for the response. The code snippet I sent deals with new style
>classes only so I assume that in some cases isinstance falls back to
>old-style-like handling which then asks for __bases__ and __class__ etc,
>possibly incorrectly so on new s
At 05:16 PM 6/26/2006 -0700, Martin Maly wrote:
> >>> class D(object):
>... def getclass(self):
>... print "D.getclass"
>... return C
>... __class__ = property(getclass)
>...
> >>> isinstance(D(), D)
>True
> >>> isinstance(D(), C)
>D.getclass
>True
>
>isinstance in this case
Message-
From: Greg Ewing [mailto:[EMAIL PROTECTED]
Sent: Monday, June 26, 2006 8:00 PM
To: Martin Maly
Cc: python-dev@python.org
Subject: Re: [Python-Dev] Semantic of isinstance
Martin Maly wrote:
>>>>isinstance(D(), D)
>
> True
>
>>>>isinstance(D(), C)
>
Martin Maly wrote:
isinstance(D(), D)
>
> True
>
isinstance(D(), C)
>
> D.getclass
> True
This looks like a new/old class thing. Presumably once
everything is changed over to new-style classes, this
inconsistency will go away. And from the current behaviour,
it looks like __class__ and
Hello Python Dev,
I am trying to understand the correct semantic of the isinstance built-in
function and while doing so, I came across few cases which raise some questions.
1) First example - a class instance pretends to have different class via
__class__.
>>> class D(object):
... def getc
15 matches
Mail list logo
