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[gitmo/MooseX-Singleton.git] / lib / MooseX / Singleton / Role / Meta / Method / Constructor.pm

package MooseX::Singleton::Role::Meta::Method::Constructor;
use Moose::Role;

our $VERSION = '0.23';
$VERSION = eval $VERSION;

override _initialize_body => sub {
    my $self = shift;

    # TODO:
    # the %options should also include a both
    # a call 'initializer' and call 'SUPER::'
    # options, which should cover approx 90%
    # of the possible use cases (even if it
    # requires some adaption on the part of
    # the author, after all, nothing is free)
    my $source = 'sub {';
    $source .= "\n" . 'my $class = shift;';

    $source .= "\n"
        . 'my $existing = do { no strict "refs"; no warnings "once"; \${"$class\::singleton"}; };';
    $source .= "\n" . 'return ${$existing} if ${$existing};';

    $source .= "\n" . 'return $class->Moose::Object::new(@_)';
    $source
        .= "\n"
        . '    if $class ne \''
        . $self->associated_metaclass->name . '\';';

    $source .= $self->_generate_params( '$params', '$class' );
    $source .= $self->_generate_instance( '$instance', '$class' );
    $source .= $self->_generate_slot_initializers;

    $source .= ";\n" . $self->_generate_triggers();
    $source .= ";\n" . $self->_generate_BUILDALL();

    $source .= ";\n" . 'return ${$existing} = $instance';
    $source .= ";\n" . '}';
    warn $source if $self->options->{debug};

    my $attrs = $self->_attributes;

    my @type_constraints
        = map { $_->can('type_constraint') ? $_->type_constraint : undef }
        @$attrs;

    my @type_constraint_bodies
        = map { defined $_ ? $_->_compiled_type_constraint : undef; }
        @type_constraints;

    my ( $code, $e ) = $self->_compile_code(
        code        => $source,
        environment => {
            '$meta'                   => \$self,
            '$attrs'                  => \$attrs,
            '@type_constraints'       => \@type_constraints,
            '@type_constraint_bodies' => \@type_constraint_bodies,
        },
    );

    $self->throw_error(
        "Could not eval the constructor :\n\n$source\n\nbecause :\n\n$e",
        error => $e, data => $source )
        if $e;

    $self->{'body'} = $code;
};

# Ideally we'd be setting this in the constructor, but the new() methods in
# what the parent classes are not well-factored.
#
# This is all a nasty hack, though. We need to fix Class::MOP::Inlined to
# allow constructor class roles to say "if the parent class has role X,
# inline".
override _expected_method_class => sub {
    my $self = shift;

    my $super_value = super();
    if ( $super_value eq 'Moose::Object' ) {
        for my $parent ( map { Class::MOP::class_of($_) }
            $self->associated_metaclass->superclasses ) {
            return $parent->name
                if $parent->is_anon_class
                    && grep { $_->name eq 'Moose::Object' }
                    map { Class::MOP::class_of($_) } $parent->superclasses;
        }
    }

    return $super_value;
};

no Moose::Role;

1;

__END__

=pod

=head1 NAME

MooseX::Singleton::Role::Meta::Method::Constructor - Constructor method role for MooseX::Singleton

=head1 DESCRIPTION

This role overrides the generated object C<new> method so that it returns the
singleton if it already exists.

=cut