Confused again

[Steven Taschuk]

Quoth Duncan Smith:
  [...]
> p.s. Thanks also to Steven, and is there any detailed guidance available on
> overloading operators?  I've read the documentation and had a Google, but
> there's still a few things I'm not clear about.  [...]

I use section 3.3 of the Language Reference, "Special method
names", which is good documentation.  I don't know of a more
tutorial-style document for these questions, I'm afraid.

> [...] ie. Steven sorted out my
> immediate problem (posted the day before last), but I'm still not 100% sure
> how I got a returned value of 0 when my code would appear to return 1.

The return values of __cmp__ and __eq__ follow different
conventions because they serve different purposes.  __cmp__ tests
for order, returning
    -1 if x < y    0 if x == y    1 if x > y
while __eq__ merely tests for equality, returning
    0 if x != y    1 if x == y
Thus a translation step is needed if you want to implement == in
terms of __cmp__.  It is this translation step which changed the 1
your __cmp__ returned into a 0.

In other words: your code returned 1, but not to the code which
did the x == y test.  Rather, this 1 was returned to the code in
the interpreter which implements ==; that code thought that 1 was
following the __cmp__ convention, and so translated it to the
__eq__ convention and returned the result (0) to the code which
did the x == y test.

-- 
Steven Taschuk                          staschuk at telusplanet.net
"Its force is immeasurable.  Even Computer cannot determine it."
                            -- _Space: 1999_ episode "Black Sun"