[Cuis-dev] Parser gets confused when using $| in binary selectors

Fri May 13 09:41:37 PDT 2022

So we did not have to introduce the @- selectors & co...

Le ven. 13 mai 2022 à 18:40, Nicolas Cellier <
nicolas.cellier.aka.nice at gmail.com> a écrit :

> The choice in Squeak was to warn only in interactive mode: the interactive
> compiler proposes a choice @ or @- or cancel, and it automatically correct
> source by inserting a space either before -2 or before 2.
> In non interactive mode, it continues to interpret it as 1@(-2) for
> backward compatibility.
> (For example Compiler evaluate: '1 at -2').
>
> Le ven. 13 mai 2022 à 18:28, Luciano Notarfrancesco via Cuis-dev <
> cuis-dev at lists.cuis.st> a écrit :
>
>> I wouldn’t implement @- *- etc in Number, that would be even more
>> confusing and reinforce bad style, I think. And ‘- 2’ compiling as -2 is
>> kind of weird too, maybe shouldn’t be allowed.
>>
>> On Fri, 13 May 2022 at 10:02 PM Hernan Wilkinson <
>> hernan.wilkinson at 10pines.com> wrote:
>>
>>> I would go back to the original behavior. if 1 @- 2 sends the message @-
>>> to 1 then that message will have to be implemented in Number to get the
>>> expected behavior, and that will happen with 1 *- 2 and 1 /- 2 and so on.
>>> This is a case where we have to be pragmatic and we have to prioritize
>>> how these messages are modeling the arithmetic of numbers.
>>> For me, this is an example where a special case in the syntax makes it
>>> more easy to use, closer to the domain problem where those messages are
>>> used 99% of the time (mathematic) and that will generate the least number
>>> of surprises.
>>> We already have problems explaining why 3 + 4 * 5 is not 23 but 35, I
>>> can not imagine myself explaining why 1 at -2 is not the same as 1 at - 2
>>> when -2 and - 2 are the same.
>>> And also, I think we have to give credit to the people that defined this
>>> behavior a long (Dan Ingalls & co). For sure they had this same discussion
>>> and they decided to go this way for a reason, and the reason for me has to
>>> do with what I mentioned earlier.
>>> Going back to the original behavior makes the behavior of these messages
>>> more natural and it will maintain compatibility with other Squeak
>>> descendant Smalltalks.
>>>
>>>
>>> On Fri, May 13, 2022 at 11:38 AM Luciano Notarfrancesco <
>>> luchiano at gmail.com> wrote:
>>>
>>>> Sounds good to me, but not a requirement for my use case, if you think
>>>> it would complicate the parser you don’t need to do it (at least not for
>>>> me).
>>>>
>>>> On Fri, 13 May 2022 at 9:31 PM Juan Vuletich <JuanVuletich at zoho.com>
>>>> wrote:
>>>>
>>>>> I'm pretty sure I can tweak the parser to treat specially $- as last
>>>>> char of a binary selector, so that
>>>>>
>>>>> 1 at -2 creates a Point.
>>>>> 1 @ -2 also creates a Point.
>>>>> 1 @- 2 (note the space between - and 2) sends #@-, whatever that might
>>>>> mean.
>>>>>
>>>>> I know it wouldn't be strictly ANSI, but that shouldn't be too
>>>>> important.
>>>>>
>>>>> Do you folks think this would be reasonable behavior?
>>>>>
>>>>> Thanks,
>>>>>
>>>>>
>>>>> On 5/13/2022 11:07 AM, Luciano Notarfrancesco via Cuis-dev wrote:
>>>>>
>>>>> Can you think of other characters that could be problematic when
>>>>> allowing them in binary selectors? I don’t use selectors ending with $-,
>>>>> and I agree that the original behavior is more convenient and intuitive.
>>>>> The only disadvantage of keeping the original behavior for this case would
>>>>> be not being ANSI compliant, not a problem for me.
>>>>>
>>>>> On Fri, 13 May 2022 at 8:58 PM Luciano Notarfrancesco <
>>>>> luchiano at gmail.com> wrote:
>>>>>
>>>>> Personally I don’t mind if we decide to make an exception for the
>>>>> special case of $-, but only for that character, because I want to have
>>>>> more options available for binary operators (for example with $|).
>>>>>
>>>>> On Fri, 13 May 2022 at 8:53 PM Hernan Wilkinson <
>>>>> hernan.wilkinson at 10pines.com> wrote:
>>>>>
>>>>> Even more... this change makes things like: 1*-2 or 1/-2 or 1//-2 or
>>>>> 1+-2, etc etc etc to generate an error.
>>>>> I think it does not make sense.... any common programmer will expect
>>>>> 1*-2 to return -2 and not an error.
>>>>> I think we should get back to the previous behavior.
>>>>>
>>>>> What do you think?
>>>>>
>>>>> Hernan.
>>>>>
>>>>> On Fri, May 13, 2022 at 10:34 AM Hernan Wilkinson <
>>>>> hernan.wilkinson at 10pines.com> wrote:
>>>>>
>>>>> Hi all!
>>>>>  I'm just wondering why you guys think that having @- as a unary
>>>>> selector is better than interpreting it as valid for a negative y of a
>>>>> point...
>>>>>  I mean, it is much more common to write 1 at -1 as a point whose y is
>>>>> -1 than to use @- as a selector...
>>>>>  Newcomers will have bit time problems to understand why 1 at -1 does
>>>>> not generate a point with a -1 as the y, unless the @- message is
>>>>> implemented in Point to create a point with the negation of the parameter
>>>>> which is for me an unnecessary indirection...
>>>>>  I mean, what other class is going to implement a message such as @- ?
>>>>>  It seems to me more useful the behavior we had previous to this
>>>>> change.
>>>>>
>>>>> Hernan.
>>>>>
>>>>>
>>>>> On Fri, May 13, 2022 at 9:52 AM Luciano Notarfrancesco via Cuis-dev <
>>>>> cuis-dev at lists.cuis.st> wrote:
>>>>>
>>>>> If you don't mind, I think these printOns look better (either one)
>>>>>
>>>>> On Fri, May 13, 2022 at 2:36 AM Luciano Notarfrancesco <
>>>>> luchiano at gmail.com> wrote:
>>>>>
>>>>> Oh, great, thanks! I was just thinking that “1@(-1)” could have been
>>>>> a better choice for the fix, and that maybe we should have a preference to
>>>>> avoid overwriting timestamp and other people’s initials when we do trivial
>>>>> changes like this.
>>>>>
>>>>>
>>>>> On Fri, 13 May 2022 at 3:41 AM Juan Vuletich <JuanVuletich at zoho.com>
>>>>> wrote:
>>>>>
>>>>> Thanks Folks!
>>>>>
>>>>> Luciano, I just pushed your changes. I also found an instance of '\\-'
>>>>> that I fixed too. There are several changes required for optional packages
>>>>> in the Cuis-Smalltalk organization. Will push them tomorrow.
>>>>>
>>>>> WRT to Decompiler, decompiled code is actually OK, with a space after
>>>>> binary selectors. What was wrong was the #storeString of literal Points.
>>>>> Fixed Point>>#printOn: for that. Now DecompilerTests pass.
>>>>>
>>>>> Cheers!
>>>>>
>>>>>
>>>>> On 5/9/2022 3:21 PM, Luciano Notarfrancesco via Cuis-dev wrote:
>>>>>
>>>>> Martin,
>>>>> Thanks for the very detailed explanation! I went ahead and replaced
>>>>> '@-' with '@ -' in the image and the tests. There are still 10 tests
>>>>> producing errors because the decompiler decompiles it without the space,
>>>>> tho.
>>>>>
>>>>>
>>>>> On Mon, May 9, 2022 at 5:04 PM Martin McClure <martin at hand2mouse.com>
>>>>> wrote:
>>>>>
>>>>> The ANSI Smalltalk grammar says that "@-" should be a valid binary
>>>>> selector, and would require whitespace in "1@ -1" to interpret the
>>>>> argument as a literal negative one.
>>>>>
>>>>> The Blue Book grammar, though, does not allow "@-" as a binary
>>>>> selector. The Blue Book grammar, as printed, also does not allow "," as a
>>>>> binary selector, even though that was clearly used as a binary selector in
>>>>> Smalltalk-80. The Blue Book grammar also does not talk about whitespace at
>>>>> all, even though that is clearly required in some places, so the Blue Book
>>>>> is a bit fuzzier than one would want as a grammar reference.
>>>>>
>>>>> Going with ANSI-like grammar and putting a space in expressions like
>>>>> "1 @- 1" makes more sense to me. Allows more valid selectors, and the code
>>>>> is more readable with the whitespace.
>>>>>
>>>>> Regards,
>>>>> -Martin
>>>>>
>>>>> On 5/9/22 03:48, Luciano Notarfrancesco via Cuis-dev wrote:
>>>>>
>>>>> After this change '1 at -1' is parsed as a binary message #@-, and this
>>>>> causes some base image tests to fail. Should we add a space between @ and
>>>>> -1 or should we fix the parser?
>>>>>
>>>>> On Fri, May 6, 2022 at 1:56 PM Luciano Notarfrancesco <
>>>>> luchiano at gmail.com> wrote:
>>>>>
>>>>> That was quick. Thanks a lot!
>>>>>
>>>>> On Fri, 6 May 2022 at 8:55 PM Juan Vuletich <JuanVuletich at zoho.com>
>>>>> wrote:
>>>>>
>>>>> On 5/6/2022 10:48 AM, Luciano Notarfrancesco via Cuis-dev wrote:
>>>>>
>>>>> I’m not sure I was clear, I meant a method implementing those
>>>>> messages, not sending those messages.
>>>>>
>>>>> On Fri, 6 May 2022 at 1:22 PM Luciano Notarfrancesco <
>>>>> luchiano at gmail.com> wrote:
>>>>>
>>>>> I’m getting “Argument name expected” when trying to compile a method
>>>>> with selector <|. On the other hand, |>, | and || all compile fine as
>>>>> binary selectors, but || breaks syntax highlighting.
>>>>>
>>>>>
>>>>> Sure. Fixes at GitHub now.
>>>>>
>>>>> A small detail: Now an empty temporal declaration `||` is parsed as a
>>>>> binary selector, and therefore marked as invalid. Not a big deal. We'd just
>>>>> remove any such.
>>>>>
>>>>> Cheers,
>>>>>
>>>>> --
>>>>> Juan Vuletichwww.cuis-smalltalk.orghttps://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Devhttps://github.com/jvuletichhttps://www.linkedin.com/in/juan-vuletich-75611b3https://independent.academia.edu/JuanVuletichhttps://www.researchgate.net/profile/Juan-Vuletichhttps://patents.justia.com/inventor/juan-manuel-vuletichhttps://twitter.com/JuanVuletich
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Juan Vuletichwww.cuis-smalltalk.orghttps://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Devhttps://github.com/jvuletichhttps://www.linkedin.com/in/juan-vuletich-75611b3https://independent.academia.edu/JuanVuletichhttps://www.researchgate.net/profile/Juan-Vuletichhttps://patents.justia.com/inventor/juan-manuel-vuletichhttps://twitter.com/JuanVuletich
>>>>>
>>>>> --
>>>>> Cuis-dev mailing list
>>>>> Cuis-dev at lists.cuis.st
>>>>> https://lists.cuis.st/mailman/listinfo/cuis-dev
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> <https://10pines.com/> Hernán Wilkinson Software Developer & Coach
>>>>>
>>>>> Alem 896, Floor 6, Buenos Aires, Argentina
>>>>>
>>>>> +54 11 6091 3125
>>>>>
>>>>> @HernanWilkinson
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> <https://10pines.com/> Hernán Wilkinson Software Developer & Coach
>>>>>
>>>>> Alem 896, Floor 6, Buenos Aires, Argentina
>>>>>
>>>>> +54 11 6091 3125
>>>>>
>>>>> @HernanWilkinson
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Juan Vuletichwww.cuis-smalltalk.orghttps://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Devhttps://github.com/jvuletichhttps://www.linkedin.com/in/juan-vuletich-75611b3https://independent.academia.edu/JuanVuletichhttps://www.researchgate.net/profile/Juan-Vuletichhttps://patents.justia.com/inventor/juan-manuel-vuletichhttps://twitter.com/JuanVuletich
>>>>>
>>>>>
>>>
>>> --
>>> <https://10pines.com/>Hernán WilkinsonSoftware Developer & Coach
>>>
>>> Alem 896, Floor 6, Buenos Aires, Argentina
>>>
>>> +54 11 6091 3125
>>>
>>> @HernanWilkinson
>>>
>> --
>> Cuis-dev mailing list
>> Cuis-dev at lists.cuis.st
>> https://lists.cuis.st/mailman/listinfo/cuis-dev
>>
>
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