[Newbies] Does Set respect ordering?

[Nicola Mingotti]

Hi,

The "set" is a mathematical object which is defined by what it contains, 
there isn't any order concept in it.

So, by definition of set: {1,2,3} = {2,3,1}

It makes not even sense to ask what is the first element of a set, 
because there is no order in it.

So, I guess Christoph is giving you the right hint, keep working with 
OrderedCollection.

Then, you may open your Squeak, on top of the Window select Help -> 
Terse Guide To Squeak
and check ouy "Bag" and "Set" sections.

bye
n.



On 2/11/20 7:11 AM, Thiede, Christoph wrote:
>
> Hi tty,
>
>
> Set does not guarantee the order of elements. It's an implementation 
> detail. If you only need to remove duplicates, have a look at 
> #withoutDuplicates.
>
> <http://www.hpi.de/>
>
> Does this help? :-)
>
> Best,
> Christoph
> ------------------------------------------------------------------------
> *Von:* Beginners <beginners-bounces at lists.squeakfoundation.org> im 
> Auftrag von tty <gettimothy at zoho.com>
> *Gesendet:* Dienstag, 11. Februar 2020 16:07:15
> *An:* beginners at lists.squeakfoundation.org
> *Betreff:* [Newbies] Does Set respect ordering?
> Hi Folks.
>
>
> If I have an OrderedCollection and convert it to Set via asSet, am I
> guaranteed that the resulting Set contains elements in the same order 
> as the
> OrderedCollection?
>
> Here is my problem.
>
> I have an OrderedCollection with the same element in it twice. By same
> element, I mean they are the same object.
>
> *an OrderedCollection(
> A
> NESTED  TABLE CELL
>
> B
> A
> NESTED  TABLE CELL
>
> )
> *
>
> Above, the first and third elements are the same XMLElement. I now this
> because if I inspect them and then change one, the other changes.
>
> if I run asSet on the OrderedCollection, I get what I need:
>
> *a Set( A
> NESTED  TABLE CELL
>
> B)*
>
>
> In that conversion, can I rely on that Ordering being preserved?
>
> If not, a pointer to the correct select/reject/inject/detect...sort of 
> thing
> would be much appreciated.
>
> cheers.
>
>
>
>
>
>
>
> --
> Sent from: http://forum.world.st/Squeak-Beginners-f107673.html
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