Push to array as part of Struct

Miq19 has asked for the wisdom of the Perl Monks concerning the following question:

I have a data structure like

my @scales;
struct( Scale => {
    name => '$',
    offset => '$',
    foo => '$',
    index => '$',
    chords => '@',
    notes => '@'
});
[download]

I found no way on how to push data to the @chords and @notes arrays of a record with that structure. I tried f.i.

my $sref = $scales[$scale]->chords;
push @{$sref}, $found_chord . ';' . $c[1];
[download]

which runs without an issue, but leaves the array empty. If I use Dumper to show the data I get like

...
  bless( {
                   'Scale::index' => '8',
                   'Scale::notes' => [],
                   'Scale::name' => 'Major Bebop Eb',
                   'Scale::chords' => [],
                   'Scale::foo' => 'E61100',
                   'Scale::offset' => undef
                 }, 'Scale' ),
          bless( {
                   'Scale::offset' => undef,
                   'Scale::foo' => 'E61100',
                   'Scale::chords' => [],
                   'Scale::name' => 'Major Bebop F',
                   'Scale::notes' => [],
                   'Scale::index' => '9'
                 }, 'Scale' ),
...
[download]

which looks like there are just empty arrays in that struct. How is the correct push syntax here?

Comment on Push to array as part of Struct Select or Download Code

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Re: Push to array as part of Struct by choroba (Cardinal) on Sep 10, 2024 at 14:14 UTC
I guess you're working with Class::Struct. You don't show enough code so I can't tell you directly what to do, but I was able to create an array of the structures and populate an array reference inside: `#!/usr/bin/perl use warnings; use strict; use Class::Struct; use Data::Dumper; struct(Scale => { name => '$', offset => '$', foo => '$', index => '$', chords => '@', notes => '@' }); my @scales = map 'Scale'->new, 1 .. 5; push @{ $scales[0]->chords }, 'Ami'; print Dumper \@scales;` [download] Beginning of the output: `$VAR1 = [ bless( { 'Scale::foo' => undef, 'Scale::chords' => [ 'Ami' ], 'Scale::notes' => [], 'Scale::offset' => undef, 'Scale::name' => undef, 'Scale::index' => undef }, 'Scale' ), bless( { ...` [download] Update: Fixed the code example. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]
Re: Push to array as part of Struct by LanX (Saint) on Sep 10, 2024 at 14:14 UTC
This is very confusing code, I have trouble to find a connection between the three snippets you posted. Probably try an SSCCE instead? Edit Please try the `->@` syntax to push to deeply nested elements Debugger demo `DB<4> push $hash{key}[4]{array}->@ , 1..3 DB<5> x \%hash 0 HASH(0xb400007bea0f2180) 'key' => ARRAY(0xb400007bea0f22a0) 0 empty slot 1 empty slot 2 empty slot 3 empty slot 4 HASH(0xb400007bea0f22d0) 'array' => ARRAY(0xb400007bea0f1d08) 0 1 1 2 2 3 DB<6>` [download] Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re: Push to array as part of Struct by Fletch (Bishop) on Sep 10, 2024 at 14:57 UTC
Just a suggestion rather than rolling your own you could use Moose and traits (specifically Moose::Meta::Attribute::Native::Trait::Array) to provide an interface to your fancier, non-scalar members in your instances. The cake is a lie. The cake is a lie. The cake is a lie.	[reply]
Re: Push to array as part of Struct by Miq19 (Novice) on Sep 10, 2024 at 14:21 UTC
Uh, my bad. The syntax is exactly as I named it - my surrounding logic was wrong (the $scale index was never increased). Sorry bothering you!	[reply]

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