On Tue, 15 Mar 2005 08:32:51 -0800, Ron Garret <[EMAIL PROTECTED]> wrote:
>In article <[EMAIL PROTECTED]>,
> [EMAIL PROTECTED] (Bengt Richter) wrote:
>
>> >Did you mean type(x).__getitem__(x,y)?
>> >
>> Not if x is a classmethod,
D'oh. I meant "not if __getitem__ is a classmethod" ;-P
>
>Oh yeah, right. Duh!
>
>> >And where is this documented?
>> Between the lines in my previous post ;-)
>
>I see. I guess I wasn't asking a stupid question then :-)
>
Seriously, no ;-) It's hard to find good documentation on deep nitty-gritties.
The most reliable documentation of actual software behavior is inevitably
the code that implements it, though that often doesn't give a clue as to the
whys of the whats and hows shown.
As Raymond Hettinger says in his nice doc (which chew slowly for best nutrition
;-)
http://users.rcn.com/python/download/Descriptor.htm
"""
For objects, the machinery is in object.__getattribute__ which transforms
b.x into type(b).__dict__['x'].__get__(b, type(b)).
The implementation works through a precedence chain that gives data descriptors
priority over instance variables, instance variables priority over non-data
descriptors,
and assigns lowest priority to __getattr__ if provided.
The full C implementation can be found in PyObject_GenericGetAttr() in
Objects/object.c.
"""
The code does show what really happens ;-)
(UIAM, for types the analogous stuff is in Objects/typeobject.c)
Most documentation is probably reachable via
http://www.python.org/
and
http://www.python.org/doc/
but sometimes specific stuff is hard to find. Descriptors are
discussed in various links of
http://www.python.org/doc/newstyle.html
and IMO Raymond's
http://users.rcn.com/python/download/Descriptor.htm
is the most readable.
If you google for descrintro you will find a lot of discussion ;-)
Regards,
Bengt Richter
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