On Thu, Jan 12, 2023 at 12:00 AM Chris Muller asqueaker@gmail.com wrote:
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.
I'm with you here, there is nothing wrong with these copy methods. I just point out that you have to be very cautious of your intentions when you use them.
Best, Karl
- Chris
On Wed, Jan 11, 2023 at 7:37 AM Taeumel, Marcel Marcel.Taeumel@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@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@lists.squeakfoundation.org im Auftrag von Levente Uzonyi leves@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@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@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