break out method generation into an _eval_closure method

[gitmo/Class-MOP.git] / lib / Class / MOP / Method / Constructor.pm

package Class::MOP::Method::Constructor;

use strict;
use warnings;

use Carp         'confess';
use Scalar::Util 'blessed', 'weaken', 'looks_like_number';

our $VERSION   = '0.71_01';
$VERSION = eval $VERSION;
our $AUTHORITY = 'cpan:STEVAN';

use base 'Class::MOP::Method::Generated';

sub new {
    my $class   = shift;
    my %options = @_;

    (blessed $options{metaclass} && $options{metaclass}->isa('Class::MOP::Class'))
        || confess "You must pass a metaclass instance if you want to inline"
            if $options{is_inline};

    ($options{package_name} && $options{name})
        || confess "You must supply the package_name and name parameters $Class::MOP::Method::UPGRADE_ERROR_TEXT";

    my $self = $class->_new(\%options);

    # we don't want this creating
    # a cycle in the code, if not
    # needed
    weaken($self->{'associated_metaclass'});

    $self->initialize_body;

    return $self;
}

sub _new {
    my $class = shift;
    my $options = @_ == 1 ? $_[0] : {@_};

    bless {
        # from our superclass
        'body'                 => undef,
        'package_name'         => $options->{package_name},
        'name'                 => $options->{name},        
        # specific to this subclass
        'options'              => $options->{options} || {},
        'associated_metaclass' => $options->{metaclass},
        'is_inline'            => ($options->{is_inline} || 0),
    }, $class;
}

sub can_be_inlined { 1 }

## accessors

sub options              { (shift)->{'options'}              }
sub associated_metaclass { (shift)->{'associated_metaclass'} }

## cached values ...

sub meta_instance {
    my $self = shift;
    $self->{'meta_instance'} ||= $self->associated_metaclass->get_meta_instance;
}

sub attributes {
    my $self = shift;
    $self->{'attributes'} ||= [ $self->associated_metaclass->compute_all_applicable_attributes ]
}

## method

sub initialize_body {
    my $self        = shift;
    my $method_name = 'generate_constructor_method';

    $method_name .= '_inline' if $self->is_inline;

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

sub generate_constructor_method {
    return sub { Class::MOP::Class->initialize(shift)->new_object(@_) }
}

sub generate_constructor_method_inline {
    my $self = shift;

    my $source = 'sub {';
    $source .= "\n" . 'my $class = shift;';

    $source .= "\n" . 'return Class::MOP::Class->initialize($class)->new_object(@_)';
    $source .= "\n" . '    if $class ne \'' . $self->associated_metaclass->name . '\';';

    $source .= "\n" . 'my $params = @_ == 1 ? $_[0] : {@_};';

    $source .= "\n" . 'my $instance = ' . $self->meta_instance->inline_create_instance('$class');
    $source .= ";\n" . (join ";\n" => map {
        $self->_generate_slot_initializer($_)
    } 0 .. (@{$self->attributes} - 1));
    $source .= ";\n" . 'return $instance';
    $source .= ";\n" . '}';
    warn $source if $self->options->{debug};

    my $code;
    {
        # NOTE:
        # create the nessecary lexicals
        # to be picked up in the eval

        $code = $self->_eval_closure(
            q{my $attrs = $self->attributes;},
            $source
        );
        confess "Could not eval the constructor :\n\n$source\n\nbecause :\n\n$@" if $@;
    }
    return $code;
}

sub _generate_slot_initializer {
    my $self  = shift;
    my $index = shift;

    my $attr = $self->attributes->[$index];

    my $default;
    if ($attr->has_default) {
        # NOTE:
        # default values can either be CODE refs
        # in which case we need to call them. Or
        # they can be scalars (strings/numbers)
        # in which case we can just deal with them
        # in the code we eval.
        if ($attr->is_default_a_coderef) {
            $default = '$attrs->[' . $index . ']->default($instance)';
        }
        else {
            $default = $attr->default;
            # make sure to quote strings ...
            unless (looks_like_number($default)) {
                $default = "'$default'";
            }
        }
    } elsif( $attr->has_builder ) {
        $default = '$instance->'.$attr->builder;
    }

    if ( defined $attr->init_arg ) {
      return (
          'if(exists $params->{\'' . $attr->init_arg . '\'}){' . "\n" .
                $self->meta_instance->inline_set_slot_value(
                    '$instance',
                    ("'" . $attr->name . "'"),
                    '$params->{\'' . $attr->init_arg . '\'}' ) . "\n" .
           '} ' . (!defined $default ? '' : 'else {' . "\n" .
                $self->meta_instance->inline_set_slot_value(
                    '$instance',
                    ("'" . $attr->name . "'"),
                     $default ) . "\n" .
           '}')
        );
    } elsif ( defined $default ) {
        return (
            $self->meta_instance->inline_set_slot_value(
                '$instance',
                ("'" . $attr->name . "'"),
                 $default ) . "\n"
        );
    } else { return '' }
}

1;

__END__

=pod

=head1 NAME

Class::MOP::Method::Constructor - Method Meta Object for constructors

=head1 SYNOPSIS

  use Class::MOP::Method::Constructor;

  my $constructor = Class::MOP::Method::Constructor->new(
      metaclass => $metaclass,
      options   => {
          debug => 1, # this is all for now
      },
  );

  # calling the constructor ...
  $constructor->body->execute($metaclass->name, %params);

=head1 DESCRIPTION

This is a subclass of C<Class::MOP::Method> which deals with
class constructors. This is used when making a class immutable
to generate an optimized constructor.

=head1 METHODS

=over 4

=item B<new (metaclass => $meta, options => \%options)>

=item B<options>

This returns the options HASH which is passed into C<new>.

=item B<associated_metaclass>

This returns the metaclass which is passed into C<new>.

=item B<attributes>

This returns the list of attributes which are associated with the
metaclass which is passed into C<new>.

=item B<meta_instance>

This returns the meta instance which is associated with the
metaclass which is passed into C<new>.

=item B<is_inline>

This returns a boolean, but since constructors are very rarely
not inlined, this always returns true for now.

=item B<can_be_inlined>

This method always returns true in this class. It exists so that
subclasses (like in Moose) can override and do some sort of checking
to determine whether or not inlining the constructor is safe.

=item B<initialize_body>

This creates the code reference for the constructor itself.

=back

=head2 Method Generators 

=over 4

=item B<generate_constructor_method>

=item B<generate_constructor_method_inline>

=back

=head1 AUTHORS

Stevan Little E<lt>stevan@iinteractive.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright 2006-2008 by Infinity Interactive, Inc.

L<http://www.iinteractive.com>

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

=cut