Hello David,

On Fri, Jul 3, 2020 at 3:43 PM David T. Lewis <lewis at mail.msen.com> wrote:
>
> On Mon, Jun 29, 2020 at 02:43:26AM +0200, Levente Uzonyi wrote:
> > Hi Nikolai,
> >
> > On Mon, 29 Jun 2020, Nikolay Suslov wrote:
> >
> > >Hello all,
> > >Figuring out, could we go back to the previous version of
> > >SequenceableCollection??#= method (as in Squeak 5.2), to check if the
> > >receiver is??equivalent to the otherCollection by using "self species ==
> > >otherCollection species",
> > >instead of "self class = otherCollection class"?
> >
> > IIRC there was a good reason for that change though I can't recall
> > what it was. I'm sure the mailing list remembers.
> >
>
> The change has my initials on it, and it was introduced here:
>
>   Name: Collections-dtl.821
>   Author: dtl
>   Time: 16 February 2019, 6:18:27.925895 pm
>   UUID: 9bfa29b3-5e9f-4c61-b19b-e0bb05403589
>   Ancestors: Collections-nice.820
>
>   Classes are expected to be unique in the system, but in some cases (e.g. Magma)
>   it is also useful to expect a proxy for a class to test equivalent to the
>   actual class. Therefore, in SequenceableCollection>>= use #= rather than #==
>   for the class comparison.
>
>
> The discussion on the list was here:
>
>   http://lists.squeakfoundation.org/pipermail/squeak-dev/2019-February/201600.html
>
> Dave
>
>

Thanks for finding that.
But, if you look at the previous version (sma 5/12/2000) of
SequenceableCollection>>=, it checks the equivalents of "species" (the
same 'kind' of thing in collection). So, replacing that with check
equivalents of a "class" introduces a "silent application bug",
especially in code, which expects "species" comparison in
SequenceableCollection>>= (like RFB I mentioned).
Anyway, it is ok to use and upgrade related code to #hasEqualElements:
method instead.
But someone still can find the difference, that in Set, Bitset,
SortedCollection we could use #= for checking equivalents of
"species", but in SequenceableCollection - not, starting from Squeak
5.3

Best regards,
Nikolai