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

Title: Moose required creates empty object Can't locate object method "x" via package "Point"

So I'm trying stuff from Moose::Cookbook::Basics::Point_AttributesAndSubclassing which says among other things The required => 1 parameter means that this attribute must be provided when a new object is created. A point object without coordinates doesn't make much sense, so we don't allow it.

But then a point object without coordinates is allowed

I don't get it , shouldn't this die without x/y being provided in constructor?

And then an empty Point doesn't have attributes? 

#!/usr/bin/perl --
use strict;
use warnings;
Main( @ARGV );
exit( 0 );
{
    package Point;
    use Moose;
    has 'x' => (isa => 'Int', is => 'rw', required => 1);
    has 'y' => (isa => 'Int', is => 'rw', required => 1);
    sub clear {
        my $self = shift;
        $self->x(0);
        $self->y(0);
    }
}
sub Main {
    print Point->new->dump;
    print Point->new({})->dump;
    print Point->new({})->x;
}
__END__
$VAR1 = bless( {}, 'Point' );
$VAR1 = bless( {}, 'Point' );
Can't locate object method "x" via package "Point" at - line 20.

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Re: Moose required creates empty object Can't locate object method "x" via package "Point"
by Anonymous Monk on May 18, 2015 at 10:31 UTC
    Hah missing BEGIN ... I fool 
    #!/usr/bin/perl --
use strict;
use warnings;
Main( @ARGV );
exit( 0 );
BEGIN {
    package Point;
    use Moose;
    has 'x' => (isa => 'Int', is => 'rw', required => 1);
    has 'y' => (isa => 'Int', is => 'rw', required => 1);
    sub clear {
        my $self = shift;
        $self->x(0);
        $self->y(0);
    }
}
sub Main {
    print Point->new->dump;
    print Point->new({})->dump;
    print Point->new({})->x;
}
__END__
Attribute (x) is required at C:\perl\site\lib\Moose\Object.pm line 24
        Moose::Object::new('Point') called at - line 18
        main::Main at - line 4

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[reply]
[d/l]

      You can remove a lot unnecessary "scaffolding" from your code: 

      #!/usr/bin/perl
package Point;
use Moose;

has 'x' => (isa => 'Int', is => 'rw', required => 1);
has 'y' => (isa => 'Int', is => 'rw', required => 1);

sub clear {
    my $self = shift;
    $self->x(0);
    $self->y(0);
}

package main;
use strict;
use warnings;

print Point->new->dump;
print Point->new({})->dump;
print Point->new({})->x;

__END__
Attribute (x) is required at /PATH/TO/Moose/Object.pm line 24
    Moose::Object::new('Point') called at foo.pl line 17

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      Strange things can happen when you don't put your modules into a proper lib/ dir, etc. etc. ... but i love and utilize the convenience of being able to put everything into one source file from time to time. :)

      jeffa

      L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]
[d/l]

        You can remove a lot unnecessary "scaffolding" from your code:

        What a ridiculous statement

        Strange things can happen when you don't put your modules into a proper lib/ dir, etc. etc. ...

        Nothing really strange, order of operations matters even to moose

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