[squeak-dev] Ideas about sets and dictionaries

Igor Stasenko siguctua at gmail.com
Wed Nov 11 21:56:20 UTC 2009


2009/11/11 Russell N Hyer <hrothgar.ofstingan at gmail.com>:
> Sets already contain nil,
>
> Evaluate this, for example:
>
> | badger |
>
> badger := Set new.
> badger add: 1.
> badger inspect
>
> and you'll see there are already nils!
>
No no. This is cheating. Nobody is interested in the ways how object
manages its internal state. The most interesting is
how good its public interface.
The right test to check if set contains nil is to send:

badger includes: nil.

and what Levente proposing is obviously that such test should return
true, if you send

badger add: nil

before.

> 2009/11/11, Levente Uzonyi <leves at elte.hu>:
>> Hi!
>>
>> On Wed, 11 Nov 2009, Russell N Hyer wrote:
>>
>>> So you're really talking about having two types of null?
>>>
>> No. I'm talking about letting a set contain nil. Try evaluating Set with:
>> nil. and you will see what my problem is.
>>
>>> nil being the set that contains nothing
>>>
>> nil is not a set. Set new gives you an empty set.
>>
>> Cheers,
>> Levente
>>
>>
>
>



-- 
Best regards,
Igor Stasenko AKA sig.



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