Use cases for del

[Grant Edwards]

On 2005-07-07, Leif K-Brooks <eurleif at ecritters.biz> wrote:
> Grant Edwards wrote:
>> On 2005-07-07, Leif K-Brooks <eurleif at ecritters.biz> wrote:
>>>_NOVALUE = object()
>>>class demo:
>>>    def foo(v=_NOVALUE):
>>>        if v is _NOVALUE:
>>>            return self.v
>>>        else:
>>>            self.v = v
>> 
>> 
>> Apart from the change in the logic such that the set operation
>> doesn't return a value, how is that any different?  You're just
>> creating your own non-integer-value "None" object instead of
>> using the one built in to the language.
>
> Sorry, my mistake: for some reason, I misunderstood your message as
> complaining that you couldn't do the same thing if you needed None to be
> usable as a value too.

Somebody had proposed eliminating None as a usable object and
people who use None now should just use 0, [], "", or ()
depending on the "type" of the expected value.  I was providing
an example of where I would use None in a context where an
"integer context" and where 0 wasn't a good substitue.

>>>But what's wrong with properties?
>> 
>> Huh?
>
> Why not use a property
> (http://www.python.org/2.2.1/descrintro.html#property) instead of a
> special property-like method?

Habit and the desire to make it explicit that something more is
going on that just assigning or evaluating an instance's
attribute.

-- 
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