I just recently started out on Moose and its a great OO framework not only to use but also to learn new OO concepts. One of the things I wanted to do was to do error reporting from perspective of caller during object creation. I saw that Moose has the module Moose::Error::Croak which tells Moose to override the default error reporting by croak call. I used it but it did not seem to help
Moose code - Foo.pm
package Foo;
use metaclass (
metaclass => 'Moose::Meta::Class',
error_class => 'Moose::Error::Croak',
);
use Moose;
has 'attr1' => (
is => 'rw',
isa => 'Str',
required => '1',
);
no Moose;
1;
Moose code - fooser.pl
#!/usr/bin/perl
use strict;
use warnings;
use Foo;
my $foobj = Foo->new();
This fails with error: Attribute (attr1) is required at /usr/local/lib/perl/5.8.8/Class/MOP/Class.pm line 364
which is terse than the actual stack trace if Moose::Error::Croak is not used. But it does not report it from perspective of caller. If this were a Perl 5 OO code and I had Foo.pm as:
package Foo;
use strict;
use warnings;
use Carp;
sub new {
my ($class, %args) = @_;
my $self = {};
if (! exists $args{'attr1'}) {
croak "ERR: did not provide attr1";
}
$self->{'attr1'} = $args{attr1};
bless $self, $class;
return $self;
}
1;
And if fooser.pl was executed I would have got the error:
"ERR: did not provide attr1 at fooser.pl line 6"
which is from the perspective of the caller as it points to line no. 6 of fooser.pl rather than MOP.pm's line no. 364.
How can I do this in Moose? Or am I misunderstanding something here?
One option is to use MooseX::Constructor::AllErrors.
This module collects constructor errors and prints them all together (default behaviour is to die as soon as the first error is encountered). It has a side-effect of printing from the caller's perspective.
Replace your use metaclass
with use MooseX::Constructor::AllErrors;
and the error becomes:
Attribute (attr1) is required at ./fooser.pl line 5
However, if you call Foo->new
from inside another module (e.g. Bar) and call Bar->new
in your script, the error would be more like:
Attribute (attr1) is required at Bar.pm line 8
...so it's not a complete solution.
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