On Fri, 12 Oct 2007 16:55:05 -0700, James Stroud wrote:
[snip]
> The use of __iadd__ & __isub__ as described in the article allows a neat
> shorthand, but does not function correctly in the context of new style
> classes.
>
> James
But still, this call on a descriptor::
obj.descr += val
is resolved into::
descr.__get__(obj, obj.__class__).__iadd__(val)
under the condition that ``descr.__get__``'s return value supports
`__iadd__`. After this is fully evaluated, `__set__` gets issued (as in
``descr.__set__(obj, descr_get_iadd_stuff_here)``).
Besides, you could perfectly do this without any descriptors at all::
class E(object):
def __iadd__(self, val):
print "__iadd__(%s, %s)" % (self, val)
class C(object):
e = E()
c = C()
c.e += 42
# __iadd__(<__main__.E object at 0x...>, 42)
Adding `__call__` to this implementation should be easy.
HTH,
Stargaming
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