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Re: Moose Type Constraints violations to warnings?

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From:
Jesse Luehrs
Date:
June 14, 2011 06:37
Subject:
Re: Moose Type Constraints violations to warnings?
Message ID:
20110614133710.GI26428@tozt.net
On Tue, Jun 14, 2011 at 11:03:33AM +0200, Ævar Arnfjörð Bjarmason wrote:
> On Tue, Jun 14, 2011 at 01:56, Jesse Luehrs <doy@tozt.net> wrote:
> > On Mon, Jun 13, 2011 at 06:45:10PM +0200, Ævar Arnfjörð Bjarmason wrote:
> >> On Mon, Jun 13, 2011 at 18:39, Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
> >> > For Mouse this monkeypatching would work:
> >>
> >> And this would work for Moose:
> >>
> >>     package Foo;
> >>     use Moose;
> >>     {
> >>     package Moose::Meta::Attribute;
> >>
> >>     sub verify_against_type_constraint {
> >>         my $self = shift;
> >>         my $val  = shift;
> >>
> >>         return 1 if !$self->has_type_constraint;
> >>
> >>         my $type_constraint = $self->type_constraint;
> >>
> >>         $type_constraint->check($val)
> >>             || Carp::cluck("Attribute ("
> >>                      . $self->name
> >>                      . ") does not pass the type constraint because: "
> >>                      . $type_constraint->get_message($val), data => $val, @_);
> >>     }
> >>     }
> >>
> >>     has x => (is => "ro", isa => "Int");
> >>     my $foo = Foo->new(x => "blah");
> >>     use Data::Dumper;
> >>     print Dumper $foo;
> >>
> >> And give you:
> >>
> >>     $ perl -Ilib /tmp/error.pl
> >>     Subroutine RegexpRef redefined at
> >> lib/Moose/Util/TypeConstraints/OptimizedConstraints.pm line 35.
> >>     Subroutine verify_against_type_constraint redefined at /tmp/error.pl line 6.
> >>     Attribute (x) does not pass the type constraint because:
> >> Validation failed for 'Int' with value
> >> blahdatablahinstanceFoo=HASH(0x1edadb0) at /tmp/error.pl line 14
> >>             Moose::Meta::Attribute::verify_against_type_constraint('Moose::Meta::Attribute=HASH(0x27e0078)',
> >> 'blah', 'instance', 'Foo=HASH(0x1edadb0)') called at
> >> lib/Moose/Meta/Attribute.pm line 1125
> >>             Moose::Meta::Attribute::_coerce_and_verify('Moose::Meta::Attribute=HASH(0x27e0078)',
> >> 'blah', 'Foo=HASH(0x1edadb0)') called at lib/Moose/Meta/Attribute.pm
> >> line 485
> >>             Moose::Meta::Attribute::initialize_instance_slot('Moose::Meta::Attribute=HASH(0x27e0078)',
> >> 'Moose::Meta::Instance=HASH(0x27ad5c0)', 'Foo=HASH(0x1edadb0)',
> >> 'HASH(0x1ec8f90)') called at lib/Class/MOP/Class.pm line 575
> >>             Class::MOP::Class::_construct_instance('Moose::Meta::Class=HASH(0x266bab0)',
> >> 'HASH(0x1ec8f90)') called at lib/Class/MOP/Class.pm line 548
> >>             Class::MOP::Class::new_object('Moose::Meta::Class=HASH(0x266bab0)',
> >> 'HASH(0x1ec8f90)') called at lib/Moose/Meta/Class.pm line 252
> >>             Moose::Meta::Class::new_object('Moose::Meta::Class=HASH(0x266bab0)',
> >> 'HASH(0x1ec8f90)') called at lib/Moose/Object.pm line 22
> >>             Moose::Object::new('Foo', 'x', 'blah') called at
> >> /tmp/error.pl line 23
> >>     $VAR1 = bless( {
> >>                      'x' => 'blah'
> >>                    }, 'Foo' );
> >>
> >
> > For the record, please please PLEASE don't do this. Attribute traits
> > exist for a reason.
> 
> How would you accomplish the same thing with attribute traits?

package My::Attr::Trait;
use Moose::Role;

around verify_against_type_constraint => sub {
    my $orig = shift;
    my $self = shift;
    my ($val) = @_;

    return 1 if !$self->has_type_constraint;

    my $type_constraint = $self->type_constraint;

    $type_constraint->check($val)
        || Carp::cluck("Attribute ("
                 . $self->name
                 . ") does not pass the type constraint because: "
                 . $type_constraint->get_message($val), data => $val, @_);
};

package Foo;
use Moose;

has x => (
    traits => ['My::Attr::Trait'],
    is     => 'ro',
    isa    => 'Int',
);

my $foo = Foo->new(x => "blah");
use Data::Dumper;
print Dumper $foo;

__END__
Attribute (x) does not pass the type constraint because: Validation failed for 'Int' with value "blah"datablahblahinstanceFoo=HASH(0x14db428) at test11.pl line 13
        Class::MOP::Class:::around('CODE(0x1baace0)', 'Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x1e4e390)', 'blah', 'instance', 'Foo=HASH(0x14db428)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Class/MOP/Method/Wrapped.pm line 161
        Class::MOP::Method::Wrapped::__ANON__('Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x1e4e390)', 'blah', 'instance', 'Foo=HASH(0x14db428)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Class/MOP/Method/Wrapped.pm line 91
        Moose::Meta::Class::__ANON__::SERIAL::1::verify_against_type_constraint('Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x1e4e390)', 'blah', 'instance', 'Foo=HASH(0x14db428)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Moose/Meta/Attribute.pm line 1131
        Moose::Meta::Attribute::_coerce_and_verify('Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x1e4e390)', 'blah', 'Foo=HASH(0x14db428)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Moose/Meta/Attribute.pm line 491
        Moose::Meta::Attribute::initialize_instance_slot('Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x1e4e390)', 'Moose::Meta::Instance=HASH(0x14e5130)', 'Foo=HASH(0x14db428)', 'HASH(0x14c6fc8)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Class/MOP/Class.pm line 524
        Class::MOP::Class::_construct_instance('Moose::Meta::Class=HASH(0x1de0200)', 'HASH(0x14c6fc8)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Class/MOP/Class.pm line 497
        Class::MOP::Class::new_object('Moose::Meta::Class=HASH(0x1de0200)', 'HASH(0x14c6fc8)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Moose/Meta/Class.pm line 269
        Moose::Meta::Class::new_object('Moose::Meta::Class=HASH(0x1de0200)', 'HASH(0x14c6fc8)') called at /home/doy/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/x86_64-linux/Moose/Object.pm line 28
        Moose::Object::new('Foo', 'x', 'blah') called at test11.pl line 29
$VAR1 = bless( {
                 'x' => 'blah'
               }, 'Foo' );

You could also use Moose::Util::MetaRole to apply the trait to all attributes in a class by default.

-doy

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