On 02.08.2015 15:44, jtuchel [via Smalltalk] wrote:
> I'd say it is questonable if SequenceableCollections should be
> comparable by default.
>
> is (a b c) equal or lower than (b a c) ?
> Doesn't this depend heavily on what is in the Collection and what the
> meaning of the Sequence of two Collections is?

(a b c) = (b a c) if a = b
(a b c) < (b a c) if a < b

The semantics are well defined.

Of course, it depends on what's in collection! That's the point - we
compare collections by their content.
If some elements are not comparable, we'll get DoesNotUnderstand -
expected behavior when comparing non-comparable objects.

It's the same story as with equality.

> So I'd say there is not much use in putting comparisons into the base
> class library, because there is a ton of assumptions about the
> Collections in whatever implementation one can imagine. I would assume
> that this is the job of some business object that holds objects in a
> SequenceableCollection. Don't you think?

There is only one assumption - that elements of the first collection are
comparable to the elements of the second collection.

And I think that we shouldn't multiply entities beyond necessity by
creating a class when using simple datastructure would be sufficient.

> The fact that other languages provide such an implementation doesn't
> mean much to me, to be honest. I choose a SequencableCollection in order
> to keep objects in a certain order, nothing more, nothing less.

That's why we have methods such as polynomialEval: and
asDigitsToPower:do: (and I'm not talking about extension methods) ?

> I think it is important to not get "overridden" by the fact that
> something is extremely easy to do in Smalltalk. We can easily make bad
> mistakes, just because we can.
>
> Just my 2 cents
>
> Joachim
>
> Am 02.08.15 um 14:11 schrieb webwarrior:
>
>  > I was surprised when discovered that in Pharo comparison is not
> defined for
>  > lists, arrays and similar datastructures.
>  >
>  > Because in almost every programming language (F#, Python, Javascript
> just to
>  > name few) you can compare lists, arrays, etc. By convention, the
> ordering is
>  > lexicographical, just like in strings.
>  >
>  > It took little time to add needed methods to SequencableCollection,
> but I
>  > think its better to have them in core library (core image, or how do you
>  > call it?).
>  >
>  >
>  >
>  > --
>  > View this message in context:
> http://forum.world.st/Comparison-for-SequencableCollection-tp4840704.html
>  > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

View this message in context: Re: Comparison for SequencableCollection
Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.