[Cuis-dev] Methods that return multiple values

[Luciano Notarfrancesco]

Interesting, thanks for sharing!
Actually I think it’s the same thing I did, my implementation calls
BlockClosure>>#valueWithPossibleArgs: and takes only as many arguments as
needed by the block but the array can be bigger than that (it should be
named #valueWithPossibleArguments: tho, abbreviations are ugly).


On Wed, 21 Jun 2023 at 15:37 Christian Haider via Cuis-dev <
cuis-dev at lists.cuis.st> wrote:

> I added something similar to my Values package (VW and ports).
>
> The source is
>
> SequenceableCollection>>asArgumentsIn: aBlock
>
>      "Evaluate aBlock with the receiver's elements as parameters.
>
>      aBlock takes its arguments from the receiver.
>
>      'ok'
>
>      #(1 2 3) asArgumentsIn: [:a :b :c | a + b + c]
>
>      #(1 2 3) asArgumentsIn: [:a :b | a + b]
>
>      #(1 2 3) asArgumentsIn: [:a | a]
>
>      #(1 2 3) asArgumentsIn: [42]
>
>      'not ok'
>
>      #(1 2 3) asArgumentsIn: [:a :b :c :d | a + b + c + d]
>
>      "
>
>
>
>      ^aBlock cullWithArguments: self asArray
>
>
>
> The difference is that it takes a list of any size and picks out the first
> items and binds them to the variables.
>
> I use it often for CSV processing like
>
>                 (line tokensBasedOn: $;) asArgumentsIn: [:first :second
> :y | … ].
>
>
>
> I am just a bit unhappy with the name – it is too long. It reads ok though.
>
> The pipe character is an interesting idea. I have to think about it.
>
>
>
> I am use it for a while now and I am very happy with it.
>
>
>
> Happy hacking,
>
> Christian
>
>
>
>
>
> *Von:* Cuis-dev <cuis-dev-bounces at lists.cuis.st> *Im Auftrag von *Luciano
> Notarfrancesco via Cuis-dev
> *Gesendet:* Mittwoch, 21. Juni 2023 15:13
> *An:* Discussion of Cuis Smalltalk <cuis-dev at lists.cuis.st>
> *Cc:* Luciano Notarfrancesco <luchiano at gmail.com>
> *Betreff:* [Cuis-dev] Methods that return multiple values
>
>
>
> Smalltalk doesn’t have a convention for methods returning multiple values,
> and I’m not aware of any implementation.
>
> An example of such thing is the extended gcd: ‘a xgcd: b’ returns g, s, t
> where g is the gcd, and as + bt = g. Writing methods that return multiple
> values is easy with the curly brackets syntax, Integer>>#xgcd: ends with
> something like
>
>     ^ {g. s. t}
>
> But using sending messages that return multiple values is kind of
> annoying, I end up doing something like:
>
>     xgcd := a xgcd: b.
>
>     g := xgcd at: 1.
>
>     s := xgcd at: 2.
>
>     t := xgcd at: 3
>
> Some years ago I thought about using blocks for this, but I never tried
> it. Today I just did a little experiment implementing anArray | aBlock as
> ‘^ aBlock valueWithPossibleArgs: self’ and I can do:
>
>     (a xgcd: b) | [:g :s :t| … ]
>
>
>
> This is seems quite nice already, I guess I’ll start using it and see how
> it feels. But the point of this mail is not to show a solution, but to ask
> if anyone have thought about this or if they know any nicer solutions. Any
> ideas?
> --
> Cuis-dev mailing list
> Cuis-dev at lists.cuis.st
> https://lists.cuis.st/mailman/listinfo/cuis-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.cuis.st/mailman/archives/cuis-dev/attachments/20230621/cf2e0917/attachment-0001.htm>