Re^2: Returning arrays from a package (feature qw/refaliasing/;)

Please allow me to nitpick a bit and to advertise an experimental feature

> You cannot return multiple lists from a function in Perl

well the OP is trying to return multiple array-refs not lists, and the new'ish use feature qw/refaliasing/; allows these to be assigned to multiple @arrays. (see tst2())

use strict;
use warnings;
use Data::Dump qw/pp dd/;

use feature qw/refaliasing/;
no warnings "experimental::refaliasing";


sub tst {
    (\my %args) = @_;
    pp \%args;
}

tst({a=>1,b=>2});



sub tst2 { return [1..3],[4..7] }

our (@a,@b);

(\@a,\@b) = tst2();

pp \@b;
pp \@a;
[download]

{ a => 1, b => 2 }
[4 .. 7]
[1, 2, 3]
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice}

Comment on Re^2: Returning arrays from a package (feature qw/refaliasing/;) Select or Download Code

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Re^3: Returning arrays from a package (feature qw/refaliasing/;) by jcb (Parson) on Oct 02, 2019 at 01:08 UTC
While we are nitpicking, I will note that the experimental `refaliasing` feature seems to just make references into lvalues, such that `tst2` is actually returning a flat list of arrayrefs, rather than multiple lists. You still cannot return multiple lists in Perl. Oh, and did I mention it is an experimental feature? :-)	[reply] [d/l] [select]
Re^4: Returning arrays from a package by LanX (Saint) on Oct 02, 2019 at 11:38 UTC
> such that tst2 is actually returning a flat list of arrayrefs, rather than multiple lists. > > well the OP is trying to return multiple array-refs not lists, > > > > `return(\@overall,\@electronics,\@safety);` And passing references is the canonical answer to this question. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}	[reply] [d/l]
Re^5: Returning arrays from a package by jcb (Parson) on Oct 02, 2019 at 23:41 UTC
Indeed, the OP's function does that, but OP attempts to accept them as multiple arrays at line 23: `my (@overall, @electronics, @safety) = breakouts(@products);` This mixing of metaphors needs to be fixed one way or the other, and I suggest that, since OP wants to export globals, the right way to fix it is to directly load the globals instead of creating lexicals to shadow them. I am surprised that perl does not warn about this; OP does `use warnings;`. This also leads to a third option, which is the C way of passing references to `breakouts` and having it populate the arrays passed as arguments, but I think the oft-seen quip "Keep It Simple, Stupid" applies here: `breakouts` is not some general function, but sorts specifically this data into these bins. A better architecture would involve replacing the whole thing with an SQL database (start with DBI and DBD::SQLite and move up to DBD::Pg when needed) but OP seems to want these arrays for some reason.	[reply] [d/l] [select]


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