Question about #caseOf:otherwise:

>
> Sounds very interesting :)
>
>
> In the past I have been writing the following instead:
>
>
> true caseOf: {
>
>     [aNumber isEven] -> ['That is an even number.'].
>
>     [aNumber isOdd] -> ['That is an odd number.']. 
>
> }.
>
>
> but your code is much more beautiful :)
>
> I think both variants have a contrary semantic, but on the other hand it just reads intuitive:
>
>
> aNumber caseOf: {
>    [42] -> ['That is correct.'].
>    [:n | n even] -> ['That is an even number.'].
>    [:n | n odd] -> ['That is an odd number.'].
> }.
>
>
> This would also require some changes to the Parser. If your examples compiles, I would also expect the following to run:
>
> aNumber caseOf: {
>    #even -> ['That is an even number.'].
>    #odd -> ['That is an odd number.'].
> }.

>
> Best,
> Christoph
>
> _________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> Von: Squeak-dev <[hidden email]> im Auftrag von Taeumel, Marcel
> Gesendet: Donnerstag, 15. August 2019 10:32:07
> An: gettimothy via Squeak-dev
> Betreff: [squeak-dev] Question about #caseOf:otherwise:  
> Hi all!
>
> Why isn't the following example possible?
>
> aNumber caseOf: {
>    [:n | n even] -> ['That is an even number.'].
>    [:n | n odd] -> ['That is an odd number.'].
> }.
>
> That is, why is the check "assoc key value = self" not configurable as "(x := assoc key cull: self) == true or: [x = self]"? :-)
>
> ... maybe it is a good thing that case-of statements in Smalltalk are not that powerful?
>
> Best,
> Marcel
>
>

> Le 15/08/2019 à 10:32, Marcel Taeumel a écrit :
>> Hi all!
>>
>> Why isn't the following example possible?
>>
>> aNumber caseOf: {
>> *[:n | n even]* -> ['That is an even number.'].
>> * [:n | n odd]* -> ['That is an odd number.'].
>> }.
>>
>> That is, why is the check "assoc key value = self" not configurable as
>> "(x := assoc key cull: self) == true or: [x = self]"? :-)
>>
>
> The semantics would then change, because multiple tests could return
> true, and then it would have to be clear if only one case is taken into
> account, and which one (for example, the first), or if all cases are
> considered and then all associated blocks are evaluated (sequencially?).
>
> So while nice, it seems to me that this proposal opens a can of worms...

>
>
> Von: Levente Uzonyi
> Gesendet: Donnerstag, 15. August, 13:32
> Betreff: Re: [squeak-dev] Question about #caseOf:otherwise:
> An: The general-purpose Squeak developers list
>
>
> On Thu, 15 Aug 2019, Thiede, Christoph wrote: > > Sounds very interesting :) > > > In the past I have been writing the following instead: > > > true caseOf: { > >     [aNumber isEven] -> ['That is an even number.']. > >    
> [aNumber isOdd] -> ['That is an odd number.'].  > > }. > > > but your code is much more beautiful :) > > I think both variants have a contrary semantic, but on the other hand it just reads intuitive: > > > aNumber caseOf: { >
>    [42] -> ['That is correct.']. >    [:n | n even] -> ['That is an even number.']. >    [:n | n odd] -> ['That is an odd number.']. > }. > > > This would also require some changes to the Parser. If your examples compiles, I
> would also expect the following to run: > > aNumber caseOf: { >    #even -> ['That is an even number.']. >    #odd -> ['That is an odd number.']. > }. While you could expect that to compile, the Parser is strict about the
> format, because everything (blocks, associations, the array) will be inlined, so no objects will be created for them. Without inlining, such construct would not be viable performance-wise. Levente > > Best, > Christoph > >________________________________________________________________________________________________________________________________________________________________________________________________________________________________
> _ > Von: Squeak-dev im Auftrag von Taeumel, Marcel > Gesendet: Donnerstag, 15. August 2019 10:32:07 > An: gettimothy via Squeak-dev > Betreff: [squeak-dev] Question about #caseOf:otherwise:   > Hi all! > > Why isn't the
> following example possible? > > aNumber caseOf: { >    [:n | n even] -> ['That is an even number.']. >    [:n | n odd] -> ['That is an odd number.']. > }. > > That is, why is the check "assoc key value = self" not
> configurable as "(x := assoc key cull: self) == true or: [x = self]"? :-) > > ... maybe it is a good thing that case-of statements in Smalltalk are not that powerful? > > Best, > Marcel > >
>
>
>