Steven Bethard wrote:
Mel Wilson wrote:

In article <[EMAIL PROTECTED]>,
Steven Bethard <[EMAIL PROTECTED]> wrote:

I believe what Peter Otten was pointing out is that calling __eq__ is
not the same as using ==, presumably because the code for == checks the
types of the two objects and returns False if they're different before
the __eq__ code ever gets called.



Doesn't seem to:

[snip]

Check his example:

http://mail.python.org/pipermail/python-list/2004-November/252660.html

I suspect that example is due to the rule that "A op B" can be passed to any of the following, depending on the operator and the types of A and B:


A.__op__(B)
B.__op__(A)
B.__rop__(A)

The latter two get invoked when B is a proper subclass of A (using 'op' for commutative operations, and 'rop' for potentially non-commutative ones). This is so that subclasses can interact with parent classes correctly.

So, in Steven's original code, B.__eq__(A) was invoked, and returned False (since A was the parent class of B, not a subclass).

Cheers,
Nick.
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