KOBAYASHI, Hiroaki

NAME

MOP4Import::Types - fields-aware type builder for inner-type

SYNOPSIS

Create inner-types MyApp::Artist and MyApp::CD using MOP4Import::Types.

  # Define subtype Artist and CD with their fields.
  package MyApp;
  use MOP4Import::Types
    (Artist => [[fields => qw/artistid name/]]
     , CD   => [[fields => qw/cdid artistid title year/]]);

Above is an equivalent of following:

  package MyApp;
  sub Artist () {'MyApp::Artist'}
  package MyApp::Artist {
     use MOP4Import::Declare [fields => qw/artistid name/];
  }
  sub CD () {'MyApp::CD'}
  package MyApp::CD {
     use MOP4Import::Declare [fields => qw/cdid artistid title year/];
  }

You can use above types like following with compile-time field name typos detection of fields.

  sub print_artist_cds {
    (my $self, my Artist $artist) = @_; # $artist is typed.
    my @cds = $self->DB->select(
      CD => {
        artistid => $artist->{artistid}  # Checked statically
      }
    );
    foreach my CD $cd (@cds) { # $cd is typed.
      print tsv($cd->{title}, $cd->{year}), "\n"; # Checked statically
    }
  }

DESCRIPTION

MOP4Import::Types is yet another protocol implementation of MOP4Import family, based on MOP4Import::Pairs and MOP4Import::Declare::Type.

In contrast to MOP4Import::Declare, which is designed to modify target module itself, this module is designed to add new inner-types to target module.

With "inner-type", I mean type declared in some module and not directly exposed as "require" able module.

"MetaObject Protocol for Import" in this module

"import()" method of this module takes name => [@pragma_list] style paired arguments and dispatch them as $myPack->declare_type($opts, $name, @pragma_list).

  use MOP4Import::Types
    (Foo => [[fields => qw/bar baz/]]
    , Cat => [[fields => qw/name birth_year/]]
    );

  # Above is equivalent of followings

  use MOP4Import::Declare::Type [type => Foo => [fields => qw/bar baz/]];
  use MOP4Import::Declare::Type [type => Cat => [fields => qw/name birth_year/]];

Type names can be imported

  package MyProject::Types;
  use MOP4Import::Types
    (User => [[fields => qw/uid name .../]]
    , Product => [[fields => qw/prodid name .../]]
    , ...
    );

  #------------
  # You can import above types in other module like following:
  #------------
  package MyProject::Web;
  use MyProject::Types qw/User Product/;

Extending types in derived class

use MOP4Import::Types::Extend instead.

Specifying base type

use MOP4Import::Types can recognize first HASH argument as option set and you can specify base type via basepkg option.

  use MOP4Import::Types +{basepkg => 'YourBaseObject'}
    Foo => [[fields => qw/.../]], ...;

SEE ALSO

MOP4Import::Declare

AUTHOR

Kobayashi, Hiroaki <hkoba@cpan.org>

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.