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Postings from June 2022
On Mon, Jun 27, 2022 at 11:11 AM Darren Duncan <darren@darrenduncan.net>
wrote:
> On 2022-06-24 3:17 p.m., Paul "LeoNerd" Evans wrote:
> > my $n = ...;
> >
> > match($n : ==) {
> > case(1) { say "It's one" }
> > case(2) { say "It's two" }
> > case(3) { say "It's three" }
> > case(4), case(5)
> > { say "It's four or five" }
> > default { say "It's something else" }
> > }
>
> I consider that the best part of this is you specify inline the exact
> comparison
> operator or sub to use, the "==" in this case, meaning that the semantics
> of the
> matching is completely explicit, rather than some implicit complicated
> logic.
>
> This should be generic and configurable in the same way map/grep/sort etc
> are.
>
I'd prefer the comparison operator per case so I can for example call isa
on an exception object to check if it's an exception object or just a
string.
That can be done using given/when from feature "switch", but as this says
it's experimental I haven't used it.
The section
https://perldoc.perl.org/perlsyn#Experimental-Details-on-given-and-when
this to explain why. To me it reads like "don't use it before v5.18". I
guess it wasn't declared non-experimental at or shortly after v5.18 because
it uses the experimental smartmatch underneath, although not mandatory.
Syntax that doesn't need to to write $_:
given|match|for|foreach ($foo) {
when|case (== 3) {
}
when|case (eq 'bar') {
}
when|case (->isa('X::File::NotFound') {
}
}
PS: I don't care what the keywords are called so I included some which are
already mentioned.
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