[Python-Dev] misbehaving __contains__

[Daniel Stutzbach]

On Jan 22, 2008 1:26 PM, tomer filiba <tomerfiliba at gmail.com> wrote:
> >>> class Foo(object):
> ...     def __contains__(self, key):
> ...             return 17
> ...     def __eq__(self, other):
> ...             return 19
> ...
> >>>
> >>> f=Foo()
> >>> f == 8
> 19
> >>> 8 in f
> True

There are many places in the C implementation where a slot returns an
int rather than a PyObject.  There other replies in this thread seem
to support altering the signature of the slot to return a PyObject.
Is this setting a precedent that _all_ slots should return a PyObject?

Consider the following third behavior:

>>> class foo(object):
...     def __len__(self):
...             return 'foo'
...
>>> x = foo()
>>> len(x)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: an integer is required

-- 
Daniel Stutzbach, Ph.D.             President, Stutzbach Enterprises LLC