Woah, I didn't know that this topic has been such a hot potato. :-)

<http://www.hpi.de/>

In my opinion, people can always abuse a (domain-specific) language to write bad code and you cannot really stop them from doing so by limiting the features of the language. Instead of banning a protocol, people should understand *why* and *when* it is a bad idea to use them. #caseOf: & Co. can be used and can be abused, so I vote for keeping and legalizing it (otherwise we have to destroy every bread knife, too).
If we stigmatize #caseOf:, we could also stigmatize or even deprecate #isKindOf: because very often, it is abused - but still, it can be useful in many situations where you need metaprogramming indeed, for example, Exception class >> #handles:.
LBNL, I often consider both concepts as the first step of a larger refactoring. Alone for this purpose, I would like to keep these selectors.

Best,
Christoph
________________________________
Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von tim Rowledge <tim at rowledge.org>
Gesendet: Sonntag, 28. März 2021 19:07:58
An: The general-purpose Squeak developers list
Betreff: Re: [squeak-dev] #identityCaseOf:



> On 2021-03-28, at 4:09 AM, Thiede, Christoph <Christoph.Thiede at student.hpi.uni-potsdam.de> wrote:
>
> @Tim:
>
> > Far too like C.
>
> Again, why please? :-) I'm not a big fan of C either, but IMO switch/select/case is not the worst concept when it allows you to eliminate some duplication.

It (both C and caseOf*) has its uses but my practical issue with caseOf* in Smalltalk is that I keep (very subjective and personal experience dependant) seeing it get used in ways that completely sidestep Smalltalk and implement bad C idiom. A bit like isKindOf: and isBlahClass.

e.g.
foo class
        caseOf: {
                [Rabbit] -> [foo doRabbitThing].
                [Fox] -> [foo doFoxThing]}
... which of course merely (badly) replicates class lookup/inheritance/message-sending. It suggests a writer that cannot escape the mental prison of C-like assault coding.

isKindOf: is a useful meta-programming idiom that I've seen used inside inner loops to do the same sort of not-message-sending. I've even had people try to justify is on the grounds that "sending messages is so slow and I want ot avoid it", which is just nuts.

isBlahClass is almost as horrible but at least has the excuse of (hopefully) being part of a not yet completed cleaning of other nastiness.

Part of the problem is that language flexibility always ends up being a tool that lets annoying people write bad FORTRAN in any language. And then somebody has to spend a too large fraction of their life trying to fix it.

tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Useful random insult:- Not enough sense to come in out of the rain.



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