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> Caching itself is no criteria, but allocating memory without giving
> the user a chance to find out should be (in this context).
> ... calling match.regs creates a
> tuple which is not there before, but cannot be removed
> afterwards. This is why I handled it separately.
Well, so why only include the tuple, and not objects inside the tuple?
They may also count in allocated memory (not often: small numbers are
shared)
Does the same criteria apply to function.func_defaults and function.doc
members? Both can be None, sizeof(None) would be added twice.
Would you say the same for property members?
class C(object):
 def setx(self): self.__x = 42
 x = property(lambda self: self.__x)
the value is not there before you call o.setx(), and cannot be removed
afterwards.
IMO, the criteria (to decide whether a container should include a
particular PyObject member in its sizeof) should not include the way the
member is created, or who created it, but only the current layout in
memory. For example: can other objects hold references to this member,
does it appear in gc.objects...
And I propose this simple algorithm: do not include any referenced
PyObject :-)