Since 2004, the test suite for Ma Object Serializer utilizes an abstract
any-Object-comparison, and has worked really well.  This shows enough about
how it does it -- basically brute force.

[image: comparing-object-equivalence.png]

The above is the abstract equivalence test implementation on Object which,
yes, a lot of classes have to override.  But, it's not hard.
Intimidation by the implementation should not be the (or, even a) deciding
factor about whether Text equivalence should honor attributes.

Re: copying -- there is no veryVeryDeepCopy, and there's nothing wrong with
having all of #shallowCopy, #copy, #deepCopy vs. #veryDeepCopy.  The former
is part of the Smalltalk language that generally goes +1 level deeper than
regular #copy, whereas #veryDeepCopy is used for the Prototype design
pattern, which is the fundamental design property of Morphic.

 - Chris

On Wed, Jan 11, 2023 at 7:37 AM Taeumel, Marcel <Marcel.Taeumel at hpi.de>
wrote:

> Hi Christoph --
>
> At this point, let's not fiddle with Text >> #=.
>
> I think that comparing sets of attributes with each other can be as tricky
> as comparing morphs, unless you restrict yourself to very simple emphasis
> (bold/italic/...).
>
> Identity-vs-state will bite you for "non-literal" attributes:
> - PluggableTextAttribute (i.e., compiled code, bindings, complex objects,
> ...)
> - TextFontReference (i.e., various font properties, form-set fonts, pixel
> comparison?, ...)
> - TextAnchor (i.e., morphs ...)
>
> Thus, the very mechanism of text properties is so flexible that
> implementing a useful comparison should be done on a case-by-case basis.
> For example, compare #runs if necessary and sufficient, as suggested in the
> comment in #=.
>
> Just comparing the identity of text attributes is not worth breaking
> backwards compatibility.
>
> Best,
> Marcel
>
> Am 16.09.2020 16:44:07 schrieb Thiede, Christoph <
> christoph.thiede at student.hpi.uni-potsdam.de>:
>
> Hi Levente,
>
>
> hm, I think #= should be always commutative and transitive, everything
> else is at least confusing ...
>
>
> Can't we move that "attribute invariant" comparison rather to something
> like Text >> #sameAs:?
>
>
> Best,
>
> Christoph
> ------------------------------
> *Von:* Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
> Auftrag von Levente Uzonyi <leves at caesar.elte.hu>
> *Gesendet:* Mittwoch, 16. September 2020 15:00:28
> *An:* The general-purpose Squeak developers list
> *Betreff:* Re: [squeak-dev] FormInspector, or also: Text>>#= and its
> consequences
>
> Hi Christoph,
>
>
> On Wed, 16 Sep 2020, Thiede, Christoph wrote:
>
> >
> > Interesting, I would not have assumed that this would be only about
> performance, sounded like a more profound design decision to me.
>
> If you have a look at the comment of Text >> #=, you'll find that it's a
> design decision (no reasoning though):
>
> = other
>          "Am I equal to the other Text or String?
>          ***** Warning ***** Two Texts are considered equal if they have
> the same characters in them.  They might have completely different
> emphasis, fonts, sizes, text actions, or embedded morphs.  If you need to
> find out if one is a true copy of the other, you must do (text1 = text2
> and: [text1 runs = text2 runs])."
>
>
> Though equality with Strings is not symmetric;
>
> 'foo' asText = 'foo'. "==> true"
> 'foo' = 'foo' asText. "==> false"
>
> I don't know what relies on Text-String equality, but probably many things
> assume that Texts and Strings are somewhat interchangable (remember when
> you changed SHParserST80 >> #initializeVariablesFromContext, and Shout ran
> into errors because it expected source to be a String but got a Text?)
>
> You can't keep equality with Strings if you change #= because you'll lose
> transitivity:
>
> 'foo' asText allBold = 'foo'. "==> true"
> 'foo' asText = 'foo'. "==> true"
> 'foo' asText allBold = 'foo' asText "==> false"
>
>
> Should you decide to change #=, remember to change #hash as well, and
> rehash all hashed collections with text keys.
>
>
> Levente
>
> >
> >
> > If no one sees a problem in changing this behavior, I can try my luck.
> :-)
> >
> >
> > Best,
> >
> > Christoph
> >
> >
> __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> > Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im
> Auftrag von Taeumel, Marcel
> > Gesendet: Dienstag, 15. September 2020 16:42:11
> > An: squeak-dev
> > Betreff: Re: [squeak-dev] FormInspector, or also: Text>>#= and its
> consequences
> > Hi Christoph.
> > Performance. Change it, bench it, post the results here. :-) Please
> specify you machine and try it on a slow RaspPi, too.
> >
> > Best,
> > Marcel
> >
> >       Am 10.09.2020 20:32:34 schrieb Thiede, Christoph <
> christoph.thiede at student.hpi.uni-potsdam.de>:
> >
> >       Hi all,
> >
> >
> >       is there any old thread about the design discussion of how
> Text>>#= works? (It does not consider attributes for quality.) Has this
> decision ever been questioned?
> >
> >
> >       Naively and without an overview of any existing components that
> could rely on this implementation, I would like to question it.
> >
> >       Why should 'foo' asText allBold be equal to 'foo' asText
> addAttribute: TextURL new? With the same logic, we could also say that two
> dictionaries are equal iff they have got the same keys ...
> >
> >
> >       There is even a concrete client in the Trunk suffering from this
> design decision: Marcel's new FormInspector (and analogously,
> MorphInspector). It uses
> >
> >       TextFontReference with a FormSetFont to display a screenshot right
> in the inspector pane. Unfortunately, the pane is never updated
> automatically because even if the screenshot changes, the text morph thinks
> the old text would equal the new one. I'd like to fix that without hacking
> any workaround into
> >       the inspectors.
> > Even though this inspector implementation is a bit unusual, in my
> opinion, it shows that the current Text >> #= implementation might not be a
> perfect solution.
> >
> > I'm looking forward to your opinions.
> >
> > Best,
> > Christoph
> >
> >
> >
>
>
>
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