operator overloading

[Ken Seehof]

Thomas Wouters wrote:

> On Mon, Jun 05, 2000 at 03:02:47PM -0700, Ken Seehof wrote:
>
> > The following more closely conforms to these conventions:
>
> The return code of __cmp__ is hardly a convention! If you dont return one of
> those values, in a consistent manner, you're going to confuse the users of
> your class greatly. And possibly break things like list.sort()'s default
> sort function.

I was being facetious and forgot to add a ":-)" to the "convention" comment.  In
other words, I was trying to be nice (in a silly way) to the author of the previous
"solution" by not actually saying that the answer was completely wrong.  Hence, in
the spirit of generosity, I referred to the boolean interpretation of 0 and 1, the
meaning of ">" and "<", and the return value of __cmp__ as "conventions".

> > ...  def __cmp__(self,other):
> > ...   if self.a == other.a:
> > ...    return 0
> > ...   elif self.a < other.a:
> > ...    return -1
> > ...   else:
> > ...    return 1
>
> Good example not withstanding, you can of course write this much shorter,
> and more obvious, and less errorprone:
>
> def __cmp__(self, other):
>         return cmp(self.a, other.a)

Good point (that is how I would write it in an actual program).  Of course, your
solution hides the semantics of the __cmp__ return value, which is fine, unless you
happen to be writing an example specifically to show the semantics of the __cmp__
return value. :-)

> This will even work if __cmp__ would be changed to return different values
> ;)
>
> --
> Thomas Wouters <thomas at xs4all.net>
>
> Hi! I'm a .signature virus! copy me into your .signature file to help me spread!

- Ken Seehof
kens at sightreader.cHi! I'm a .signature virus! copy me into your .signature file to
help me spread!om

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