Support of algebraic operations on sets
Klaus D. Witzel
klaus.witzel at cobss.com
Fri Jun 15 14:56:28 UTC 2007
On Fri, 15 Jun 2007 15:50:54 +0200, Bert Freudenberg wrote:
> On Jun 15, 2007, at 14:45 , sig wrote:
>
>> actually i missing these operations for dictionaries.
>> in current implementation if you diff/union on two dictionaries,
>> you'll find out that associations play role as set elements, not keys.
>>
>> for dictionaries 'a difference: b' i get not exactly what i would
>> expect.
>
> Dictionaries are like other collections - a collection of "elements"
> (the values). The keys are only interesting for accessing - like indices
> on Arrays. #do: operates on the values. So does #select:, and
> #difference:. You wouldn't expect #difference: on an Array to work on
> its indices, would you?
Good argument. And if some solves that by (aDict keys op: bDict keys) and
aDict's values are completely different from bDict values, no cDict can
hold the "correct" values unless cDict is empty under all circumstances ;-)
/Klaus
> - Bert -
>
>
>
>
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