[issue2898] Add memory footprint query

[Robert Schuppenies]

Robert Schuppenies <okkotonushi at googlemail.com> added the comment:

I tried to implement a magic method __sizeof__() for the type object 
which should be callable for type objects and type itself.
But calling __sizeof__ results in an error message

>>> type.__sizeof__()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: descriptor '__sizeof__' of 'type' object needs an argument

Debugging it I found that type_getattro will (1) look for the
attribute in the metatype, (2) look in tp_dict of this type, and (3)
use the descriptor from the metatype.

I actually want it to perform (3), but since type is its own
metatype (2) will be triggered. This then results in the need for an
argument. The same behavior occurs for all type instances, i.e. classes.

Is my understanding correct? How would it be possible to invoke
__sizeof__() on the type 'type' and not on the object 'type'?


My first approach did the same for object, that is a magic __sizeof__() 
method linked to object, but it gets ignored when invoked on classes or
types.
Now from my understanding everything is an object, thus also
classes and types. isinstance seems to agree with me

>>> >>> isinstance(int, object)
True


Any suggestions on that?

thanks,
robert

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue2898>
_______________________________________