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List:       python-list
Subject:    Re: Would there be support for a more general cmp/__cmp__
From:       Steven Bethard <steven.bethard () gmail ! com>
Date:       2005-10-26 16:05:31
Message-ID: n-Sdna7R34LbNMLeRVn-rA () comcast ! com
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Antoon Pardon wrote:
> Christopher Subich schreef :
> 
>> Antoon Pardon wrote:
>>> >>>from decimal import Decimal
>>> >>>Zero = Decimal(0)
>>> >>>cmp( ( ) , Zero)
>>> -1
>>> >>>cmp(Zero, 1)
>>> -1
>>> >>>cmp(1, ( ) )
>>> -1
>>
>> I'd argue that the wart here is that cmp doesn't throw an exception, not 
>> that it returns inconsistent results.  This is a classic case of 
>> incomparable objects, and saying that 1 < an empty tuple is bordering on 
>> meaningless.
> 
> I wont argue with you here, but it is what python gives as now.
> Changing this behaviour is not going to happen.

FWIW, Guido has said a few times that in Python 3.0 we should "Raise an 
exception when making comparisons (other than equality and inequality) 
between two incongruent types."[1]  But yes, the behavior won't change 
in the Python 2.X series due to backwards compatibility concerns.

STeVe

[1] http://wiki.python.org/moin/Python3%2e0
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