Trouble with max() and __cmp__()

[Thomas Nelson]

My code:

class Policy(list):
def __cmp__(self,ot her):
return cmp(self.fitnes s,other.fitness )

j = Policy()
j.fitness = 3
k = Policy()
k.fitness = 1
l = Policy()
l.fitness = 5
print max([j,k,l]).fitness

prints 3, when I was expecting it to print 5. What have I done wrong?

Thanks for the help,
THN

[Wojciech =?ISO-8859-2?Q?Mu=B3a?=]

Re: Trouble with max() and __cmp__()

Thomas Nelson wrote:

My code:
>
class Policy(list):
def __cmp__(self,ot her):
return cmp(self.fitnes s,other.fitness )

Define method __gt__.

[Thomas Nelson]

Re: Trouble with max() and __cmp__()



On Jan 28, 3:13 pm, Wojciech Muła
<wojciech_m...@ poczta.null.one t.pl.invalidwro te:

>Define method __gt__.

This works, thanks. I was a little surprised though. is __cmp__ used
by any builtin functions?

Thanks,
THN

[=?UTF-8?B?Ik1hcnRpbiB2LiBMw7Z3aXMi?=]

Re: Trouble with max() and __cmp__()

Thomas Nelson schrieb:

On Jan 28, 3:13 pm, Wojciech Muła
<wojciech_m...@ poczta.null.one t.pl.invalidwro te:

>Define method __gt__.

>
This works, thanks. I was a little surprised though. is __cmp__ used
by any builtin functions?

It is used by max() if the object doesn't implement __gt__.

Regards,
Martin

[Gabriel Genellina]

Re: Trouble with max() and __cmp__()

At Sunday 28/1/2007 18:21, Thomas Nelson wrote:

><wojciech_m... @poczta.null.on et.pl.invalidwr ote:

Define method __gt__.

>
>This works, thanks. I was a little surprised though. is __cmp__ used
>by any builtin functions?

The problem is, rich comparison functions take precedence over
__cmp__, so if your base class (list in this case) already defines
rich comparison, you have to redefine them all.
For simple cases, you can just redefine __cmp__ and reimplement all
others __gt__, __lt__ etc using it.


--
Gabriel Genellina
Softlab SRL






_______________ _______________ _______________ _____
Preguntá. Respondé. Descubrí.
Todo lo que querías saber, y lo que ni imaginabas,
está en Yahoo! Respuestas (Beta).
¡Probalo ya!

http://www.yahoo.com.ar/respuestas