KiokuDB::Meta::Attribute::Lazy - Trait for lazy loaded attributes


KiokuDB documentation Contained in the KiokuDB distribution.

Index


Code Index:

NAME

Top

KiokuDB::Meta::Attribute::Lazy - Trait for lazy loaded attributes

SYNOPSIS

Top

    # in your class:

    package Foo;
    use KiokuDB::Class;

    has bar => (
        traits => [qw(KiokuDB::Lazy)],
        isa => "Bar",
        is  => "ro",
    );







    # Later:

    my $foo = $dir->lookup($id);

    # bar is not yet loaded, it will be lazily fetched during this call:
    $foo->bar;

DESCRIPTION

Top

This Moose::Meta::Attribute trait provides lazy loading on a per field basis for objects stored in KiokuDB.

Instead of using proxy objects with AUTOLOAD, overloading, or similar hacks, you can declaratively specify which attributes you want to make lazy, and this will be done cleanly through the MOP.

This is implemented by using a placeholder object, KiokuDB::Thunk which contains references to the ID and the linker, and KiokuDB::Meta::Instance will know to replace the placeholder with the actual loaded object when it is fetched from the object by an accessor.


KiokuDB documentation Contained in the KiokuDB distribution.

#!/usr/bin/perl

package KiokuDB::Meta::Attribute::Lazy;
use Moose::Role;

use Moose::Util qw(does_role);

use namespace::clean -except => 'meta';

sub Moose::Meta::Attribute::Custom::Trait::KiokuDB::Lazy::register_implementation { __PACKAGE__ }

before attach_to_class => sub {
    my ( $self, $class ) = @_;

    my $mi = $class->get_meta_instance;

    unless ( does_role( $mi, "KiokuDB::Meta::Instance" ) ) {
        $self->throw_error("Can't attach to a class whose meta instance doesn't do KiokuDB::Meta::Instance", data => $class );
    }
};

__PACKAGE__

__END__