/ 
Moose-2.0401
River stage four • 2950 direct dependents • 4061 total dependents
/ Moose::Exporter

NAME

Moose::Exporter - make an import() and unimport() just like Moose.pm

VERSION

version 2.0401

SYNOPSIS

package MyApp::Moose;

use Moose ();
use Moose::Exporter;

Moose::Exporter->setup_import_methods(
    with_meta => [ 'has_rw', 'sugar2' ],
    as_is     => [ 'sugar3', \&Some::Random::thing ],
    also      => 'Moose',
);

sub has_rw {
    my ( $meta, $name, %options ) = @_;
    $meta->add_attribute(
        $name,
        is => 'rw',
        %options,
    );
}

# then later ...
package MyApp::User;

use MyApp::Moose;

has 'name';
has_rw 'size';
thing;

no MyApp::Moose;

DESCRIPTION

This module encapsulates the exporting of sugar functions in a Moose.pm-like manner. It does this by building custom import, unimport, and init_meta methods for your module, based on a spec you provide.

It also lets you "stack" Moose-alike modules so you can export Moose's sugar as well as your own, along with sugar from any random MooseX module, as long as they all use Moose::Exporter. This feature exists to let you bundle a set of MooseX modules into a policy module that developers can use directly instead of using Moose itself.

To simplify writing exporter modules, Moose::Exporter also imports strict and warnings into your exporter module, as well as into modules that use it.

METHODS

This module provides two public methods:

Moose::Exporter->setup_import_methods(...)

When you call this method, Moose::Exporter builds custom import, unimport, and init_meta methods for your module. The import method will export the functions you specify, and can also re-export functions exported by some other module (like Moose.pm).

The unimport method cleans the caller's namespace of all the exported functions. This includes any functions you re-export from other packages. However, if the consumer of your package also imports those functions from the original package, they will not be cleaned.

If you pass any parameters for Moose::Util::MetaRole, this method will generate an init_meta for you as well (see below for details). This init_meta will call Moose::Util::MetaRole::apply_metaroles and Moose::Util::MetaRole::apply_base_class_roles as needed.

Note that if any of these methods already exist, they will not be overridden, you will have to use build_import_methods to get the coderef that would be installed.

This method accepts the following parameters:

  • with_meta => [ ... ]

    This list of function names only will be wrapped and then exported. The wrapper will pass the metaclass object for the caller as its first argument.

    Many sugar functions will need to use this metaclass object to do something to the calling package.

  • as_is => [ ... ]

    This list of function names or sub references will be exported as-is. You can identify a subroutine by reference, which is handy to re-export some other module's functions directly by reference (\&Some::Package::function).

    If you do export some other package's function, this function will never be removed by the unimport method. The reason for this is we cannot know if the caller also explicitly imported the sub themselves, and therefore wants to keep it.

  • trait_aliases => [ ... ]

    This is a list of package names which should have shortened aliases exported, similar to the functionality of aliased. Each element in the list can be either a package name, in which case the export will be named as the last namespace component of the package, or an arrayref, whose first element is the package to alias to, and second element is the alias to export.

  • also => $name or \@names

    This is a list of modules which contain functions that the caller wants to export. These modules must also use Moose::Exporter. The most common use case will be to export the functions from Moose.pm. Functions specified by with_meta or as_is take precedence over functions exported by modules specified by also, so that a module can selectively override functions exported by another module.

    Moose::Exporter also makes sure all these functions get removed when unimport is called.

  • meta_lookup => sub { ... }

    This is a function which will be called to provide the metaclass to be operated upon by the exporter. This is an advanced feature intended for use by package generator modules in the vein of MooseX::Role::Parameterized in order to simplify reusing sugar from other modules that use Moose::Exporter. This function is used, for example, to select the metaclass to bind to functions that are exported using the with_meta option.

    This function will receive one parameter: the class name into which the sugar is being exported. The default implementation is:

    sub { Class::MOP::class_of(shift) }

    Accordingly, this function is expected to return a metaclass.

You can also provide parameters for Moose::Util::MetaRole::apply_metaroles and Moose::Util::MetaRole::base_class_roles. Specifically, valid parameters are "class_metaroles", "role_metaroles", and "base_class_roles".

Moose::Exporter->build_import_methods(...)

Returns two or three code refs, one for import, one for unimport, and optionally one for init_meta, if the appropriate options are passed in.

Accepts the additional install option, which accepts an arrayref of method names to install into your exporting package. The valid options are import, unimport, and init_meta. Calling setup_import_methods is equivalent to calling build_import_methods with install => [qw(import unimport init_meta)] except that it doesn't also return the methods.

The import method is built using Sub::Exporter. This means that it can take a hashref of the form { into => $package } to specify the package it operates on.

Used by setup_import_methods.

IMPORTING AND init_meta

If you want to set an alternative base object class or metaclass class, see above for details on how this module can call Moose::Util::MetaRole for you.

If you want to do something that is not supported by this module, simply define an init_meta method in your class. The import method that Moose::Exporter generates for you will call this method (if it exists). It will always pass the caller to this method via the for_class parameter.

Most of the time, your init_meta method will probably just call Moose->init_meta to do the real work:

sub init_meta {
    shift; # our class name
    return Moose->init_meta( @_, metaclass => 'My::Metaclass' );
}

Keep in mind that build_import_methods will return an init_meta method for you, which you can also call from within your custom init_meta:

my ( $import, $unimport, $init_meta )
    = Moose::Exporter->build_import_methods(...);

sub import {
    my $class = shift;

    ...

    # You can either pass an explicit package to import into ...
    $class->$import( { into => scalar(caller) }, ... );

    ...;
}

# ... or you can use 'goto' to provide the correct caller info to the
# generated method
sub unimport { goto &$unimport }

sub init_meta {
    my $class = shift;

    ...

    $class->$init_meta(...);

    ...
}

METACLASS TRAITS

The import method generated by Moose::Exporter will allow the user of your module to specify metaclass traits in a -traits parameter passed as part of the import:

use Moose -traits => 'My::Meta::Trait';

use Moose -traits => [ 'My::Meta::Trait', 'My::Other::Trait' ];

These traits will be applied to the caller's metaclass instance. Providing traits for an exporting class that does not create a metaclass for the caller is an error.

BUGS

See "BUGS" in Moose for details on reporting bugs.

AUTHOR

Moose is maintained by the Moose Cabal, along with the help of many contributors. See "CABAL" in Moose and "CONTRIBUTORS" in Moose for details.

COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Infinity Interactive, Inc..

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.