package Moose::Cookbook::Roles::Recipe1;
-# ABSTRACT: The Moose::Role example
-
__END__
-
=pod
-=head1 SYNOPSIS
-
- package Eq;
- use Moose::Role;
-
- requires 'equal_to';
-
- sub not_equal_to {
- my ( $self, $other ) = @_;
- not $self->equal_to($other);
- }
-
- package Comparable;
- use Moose::Role;
-
- with 'Eq';
-
- requires 'compare';
-
- sub equal_to {
- my ( $self, $other ) = @_;
- $self->compare($other) == 0;
- }
-
- sub greater_than {
- my ( $self, $other ) = @_;
- $self->compare($other) == 1;
- }
-
- sub less_than {
- my ( $self, $other ) = @_;
- $self->compare($other) == -1;
- }
-
- sub greater_than_or_equal_to {
- my ( $self, $other ) = @_;
- $self->greater_than($other) || $self->equal_to($other);
- }
-
- sub less_than_or_equal_to {
- my ( $self, $other ) = @_;
- $self->less_than($other) || $self->equal_to($other);
- }
-
- package Printable;
- use Moose::Role;
-
- requires 'to_string';
-
- package US::Currency;
- use Moose;
-
- with 'Comparable', 'Printable';
-
- has 'amount' => ( is => 'rw', isa => 'Num', default => 0 );
-
- sub compare {
- my ( $self, $other ) = @_;
- $self->amount <=> $other->amount;
- }
-
- sub to_string {
- my $self = shift;
- sprintf '$%0.2f USD' => $self->amount;
- }
-
-=head1 DESCRIPTION
-
-Roles have two primary purposes: as interfaces, and as a means of code
-reuse. This recipe demonstrates the latter, with roles that define
-comparison and display code for objects.
-
-Let's start with C<Eq>. First, note that we've replaced C<use Moose>
-with C<use Moose::Role>. We also have a new sugar function, C<requires>:
-
- requires 'equal_to';
-
-This says that any class which consumes this role must provide an
-C<equal_to> method. It can provide this method directly, or by
-consuming some other role.
-
-The C<Eq> role defines its C<not_equal_to> method in terms of the
-required C<equal_to> method. This lets us minimize the methods that
-consuming classes must provide.
-
-The next role, C<Comparable>, builds on the C<Eq> role. We include
-C<Eq> in C<Comparable> using C<with>, another new sugar function:
-
- with 'Eq';
-
-The C<with> function takes a list of roles to consume. In our example,
-the C<Comparable> role provides the C<equal_to> method required by
-C<Eq>. However, it could opt not to, in which case a class that
-consumed C<Comparable> would have to provide its own C<equal_to>. In
-other words, a role can consume another role I<without> providing any
-required methods.
-
-The C<Comparable> role requires a method, C<compare>:
-
- requires 'compare';
-
-The C<Comparable> role also provides a number of other methods, all of
-which ultimately rely on C<compare>.
-
- sub equal_to {
- my ( $self, $other ) = @_;
- $self->compare($other) == 0;
- }
-
- sub greater_than {
- my ( $self, $other ) = @_;
- $self->compare($other) == 1;
- }
-
- sub less_than {
- my ( $self, $other ) = @_;
- $self->compare($other) == -1;
- }
-
- sub greater_than_or_equal_to {
- my ( $self, $other ) = @_;
- $self->greater_than($other) || $self->equal_to($other);
- }
-
- sub less_than_or_equal_to {
- my ( $self, $other ) = @_;
- $self->less_than($other) || $self->equal_to($other);
- }
-
-Finally, we define the C<Printable> role. This role exists solely to
-provide an interface. It has no methods, just a list of required methods.
-In this case, it just requires a C<to_string> method.
-
-An interface role is useful because it defines both a method and a
-I<name>. We know that any class which does this role has a
-C<to_string> method, but we can also assume that this method has the
-semantics we want. Presumably, in real code we would define those
-semantics in the documentation for the C<Printable> role. (1)
-
-Finally, we have the C<US::Currency> class which consumes both the
-C<Comparable> and C<Printable> roles.
-
- with 'Comparable', 'Printable';
-
-It also defines a regular Moose attribute, C<amount>:
-
- has 'amount' => ( is => 'rw', isa => 'Num', default => 0 );
-
-Finally we see the implementation of the methods required by our
-roles. We have a C<compare> method:
-
- sub compare {
- my ( $self, $other ) = @_;
- $self->amount <=> $other->amount;
- }
-
-By consuming the C<Comparable> role and defining this method, we gain
-the following methods for free: C<equal_to>, C<greater_than>,
-C<less_than>, C<greater_than_or_equal_to> and
-C<less_than_or_equal_to>.
-
-Then we have our C<to_string> method:
-
- sub to_string {
- my $self = shift;
- sprintf '$%0.2f USD' => $self->amount;
- }
-
-=head1 CONCLUSION
-
-Roles can be very powerful. They are a great way of encapsulating
-reusable behavior, as well as communicating (semantic and interface)
-information about the methods our classes provide.
-
-=head1 FOOTNOTES
-
-=over 4
-
-=item (1)
-
-Consider two classes, C<Runner> and C<Process>, both of which define a
-C<run> method. If we just require that an object implements a C<run>
-method, we still aren't saying anything about what that method
-I<actually does>. If we require an object that implements the
-C<Executable> role, we're saying something about semantics.
-
-=back
-
-=begin testing
-
-ok( US::Currency->does('Comparable'), '... US::Currency does Comparable' );
-ok( US::Currency->does('Eq'), '... US::Currency does Eq' );
-ok( US::Currency->does('Printable'), '... US::Currency does Printable' );
-
-my $hundred = US::Currency->new( amount => 100.00 );
-isa_ok( $hundred, 'US::Currency' );
-
-ok( $hundred->DOES("US::Currency"), "UNIVERSAL::DOES for class" );
-ok( $hundred->DOES("Comparable"), "UNIVERSAL::DOES for role" );
-
-can_ok( $hundred, 'amount' );
-is( $hundred->amount, 100, '... got the right amount' );
-
-can_ok( $hundred, 'to_string' );
-is( $hundred->to_string, '$100.00 USD',
- '... got the right stringified value' );
-
-ok( $hundred->does('Comparable'), '... US::Currency does Comparable' );
-ok( $hundred->does('Eq'), '... US::Currency does Eq' );
-ok( $hundred->does('Printable'), '... US::Currency does Printable' );
-
-my $fifty = US::Currency->new( amount => 50.00 );
-isa_ok( $fifty, 'US::Currency' );
-
-can_ok( $fifty, 'amount' );
-is( $fifty->amount, 50, '... got the right amount' );
-
-can_ok( $fifty, 'to_string' );
-is( $fifty->to_string, '$50.00 USD', '... got the right stringified value' );
-
-ok( $hundred->greater_than($fifty), '... 100 gt 50' );
-ok( $hundred->greater_than_or_equal_to($fifty), '... 100 ge 50' );
-ok( !$hundred->less_than($fifty), '... !100 lt 50' );
-ok( !$hundred->less_than_or_equal_to($fifty), '... !100 le 50' );
-ok( !$hundred->equal_to($fifty), '... !100 eq 50' );
-ok( $hundred->not_equal_to($fifty), '... 100 ne 50' );
-
-ok( !$fifty->greater_than($hundred), '... !50 gt 100' );
-ok( !$fifty->greater_than_or_equal_to($hundred), '... !50 ge 100' );
-ok( $fifty->less_than($hundred), '... 50 lt 100' );
-ok( $fifty->less_than_or_equal_to($hundred), '... 50 le 100' );
-ok( !$fifty->equal_to($hundred), '... !50 eq 100' );
-ok( $fifty->not_equal_to($hundred), '... 50 ne 100' );
-
-ok( !$fifty->greater_than($fifty), '... !50 gt 50' );
-ok( $fifty->greater_than_or_equal_to($fifty), '... !50 ge 50' );
-ok( !$fifty->less_than($fifty), '... 50 lt 50' );
-ok( $fifty->less_than_or_equal_to($fifty), '... 50 le 50' );
-ok( $fifty->equal_to($fifty), '... 50 eq 50' );
-ok( !$fifty->not_equal_to($fifty), '... !50 ne 50' );
-
-## ... check some meta-stuff
-
-# Eq
-
-my $eq_meta = Eq->meta;
-isa_ok( $eq_meta, 'Moose::Meta::Role' );
-
-ok( $eq_meta->has_method('not_equal_to'), '... Eq has_method not_equal_to' );
-ok( $eq_meta->requires_method('equal_to'),
- '... Eq requires_method not_equal_to' );
-
-# Comparable
-
-my $comparable_meta = Comparable->meta;
-isa_ok( $comparable_meta, 'Moose::Meta::Role' );
-
-ok( $comparable_meta->does_role('Eq'), '... Comparable does Eq' );
-
-foreach my $method_name (
- qw(
- equal_to not_equal_to
- greater_than greater_than_or_equal_to
- less_than less_than_or_equal_to
- )
- ) {
- ok( $comparable_meta->has_method($method_name),
- '... Comparable has_method ' . $method_name );
-}
-
-ok( $comparable_meta->requires_method('compare'),
- '... Comparable requires_method compare' );
-
-# Printable
-
-my $printable_meta = Printable->meta;
-isa_ok( $printable_meta, 'Moose::Meta::Role' );
-
-ok( $printable_meta->requires_method('to_string'),
- '... Printable requires_method to_string' );
-
-# US::Currency
-
-my $currency_meta = US::Currency->meta;
-isa_ok( $currency_meta, 'Moose::Meta::Class' );
-
-ok( $currency_meta->does_role('Comparable'),
- '... US::Currency does Comparable' );
-ok( $currency_meta->does_role('Eq'), '... US::Currency does Eq' );
-ok( $currency_meta->does_role('Printable'),
- '... US::Currency does Printable' );
-
-foreach my $method_name (
- qw(
- amount
- equal_to not_equal_to
- compare
- greater_than greater_than_or_equal_to
- less_than less_than_or_equal_to
- to_string
- )
- ) {
- ok( $currency_meta->has_method($method_name),
- '... US::Currency has_method ' . $method_name );
-}
-
-=end testing
+=head1 RENAMED TO L<Moose::Cookbook::Roles::Comparable_CodeReuse>
=cut
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