Moose problem.

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

Why does give 'Use of uninitialized value in print' instead of printing "two"?

use strict;
use warnings;

package Stuff {
    use Moose;

    has 'options' => (
    traits  => ['Array'],
    is      => 'ro',
    isa     => 'ArrayRef[Str]',
    default => sub { [] },
    handles => {
        all_options    => 'elements',
        add_option     => 'push',
        map_options    => 'map',
        filter_options => 'grep',
        find_option    => 'first',
        get_option     => 'get',
        join_options   => 'join',
        count_options  => 'count',
        has_options    => 'count',
        has_no_options => 'is_empty',
        sorted_options => 'sort',
    },
    );

    sub test {
        my ($self, $arg) = @_;
        $self->get_option($arg);
    }

    no Moose;
    1;
};

my $s = Stuff->new({elements => [ qw/one two three/ ] });
print $s->test(1);
[download]

Comment on Moose problem. Download Code

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Re: Moose problem. by choroba (Cardinal) on Dec 17, 2014 at 09:06 UTC
To initialise an object, pass the attribute name to the constructor, not a method name: `my $s = Stuff->new({options => [ qw/one two three/ ] });` [download] You could have used Data::Dumper, it would have shown you $s has no options populated. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^2: Moose problem. by Anonymous Monk on Dec 17, 2014 at 12:06 UTC
"To initialise an object, pass the attribute name to the constructor, not a method name:" Thanks. (Shame about the lack of error handling!)	[reply]
Re^3: Moose problem. by choroba (Cardinal) on Dec 17, 2014 at 12:14 UTC
Shame about the lack of error handling! MooseX::StrictConstructor لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply]
Re: Moose problem. by Anonymous Monk on Dec 17, 2014 at 09:10 UTC
Because `$self->get_option( 1 );` returns undef? Try Data::Dump::dd( $s ); and see what you get	[reply] [d/l]