1 package LaTeX::TikZ::Meta::TypeConstraint::Autocoerce;
8 LaTeX::TikZ::Meta::TypeConstraint::Autocoerce - Type constraint metaclass that autoloads type coercions.
16 our $VERSION = '0.02';
20 # The target class of the autocoercion (cannot be changed)
28 use LaTeX::TikZ::Meta::TypeConstraint::Autocoerce;
29 use Mouse::Util::TypeConstraints;
30 register_type_constraint(
31 LaTeX::TikZ::Meta::TypeConstraint::Autocoerce->new(
32 name => 'X::Autocoerce',
33 target => find_type_constraint(__PACKAGE__),
34 mapper => sub { join '::', __PACKAGE__, 'From', $_[1] },
37 __PACKAGE__->meta->make_immutable;
40 # The class that does the coercion (cannot be changed)
46 isa => 'X::Autocoerce',
50 __PACKAGE__->meta->make_immutable;
53 # Another class the user wants to use instead of X (cannot be changed)
61 __PACKAGE__->meta->make_immutable;
64 # The autocoercion class, defined by the user in X/From/Z.pm
67 use Mouse::Util::TypeConstraints;
68 coerce 'X::Autocoerce'
70 => via { X->new(id => int $_->id) };
73 my $z = Z->new(id => 123);
74 my $y = Y->new(x => $z);
79 When a type coercion is attempted, this type constraint metaclass tries to autoload a specific module which is supposed to contain the actual coercion code.
80 This allows you to declare types that can be replaced (through coercion) at the end user's discretion.
82 It only supports L<Mouse> currently.
84 Note that you will need L<Mouse::Util::TypeConstraints/register_type_constraint> to install this type constraint, which is only available starting L<Mouse> C<0.63>.
88 use Scalar::Util qw<blessed>;
92 use LaTeX::TikZ::Tools;
98 This class inherits from L<Mouse::Meta::TypeConstraint>.
102 extends 'Mouse::Meta::TypeConstraint';
108 The name of the type constraint.
109 This must be the target of both the classes that want to use the autocoercion feature and the user defined coercions in the autoloaded classes.
111 This attribute is inherited from the L<Mouse> type constraint metaclass.
115 A code reference that maps an object class name to the name of the package in which the coercion can be found, or C<undef> to disable coercion for this class name.
116 It is called with the type constraint object as first argument, followed by the class name.
128 A type constraint that defines into what the objects are going to be coerced.
129 Objects satisfying this type constraint will be automatically considered as valid and will not be coerced.
130 If it is given as a plain string, then a type constraint with the same name is searched for in the global type constraint registry.
136 isa => 'Mouse::Meta::TypeConstraint',
140 my $target_tc = __PACKAGE__->meta->find_attribute_by_name('target')
145 =head2 C<< new name => $name, mapper => $mapper, target => $target >>
147 Constructs a type constraint object that will attempt to autocoerce objects that are not valid according to C<$target> by loading the class returned by C<$mapper>.
151 around 'new' => sub {
152 my ($orig, $class, %args) = @_;
154 unless (exists $args{mapper}) {
155 $args{mapper} = sub { join '::', $_[0]->target->name, $_[1] };
158 my $target = delete $args{target};
159 unless (blessed $target) {
160 my $target_name = defined $target ? "target $target" : 'undefined target';
161 $target = LaTeX::TikZ::Tools::type_constraint($target) if defined $target;
162 Carp::confess("No meta object for $target_name") unless defined $target;
164 $target_tc->assert_valid($target);
165 $args{target} = $target;
167 $args{constraint} = Sub::Name::subname('_constraint' => sub {
170 # Remember that when ->check is called inside coerce, a return value of 0
171 # means that coercion should take place, while 1 signifies that the value is
172 # already OK. Thus we should return true if and only if $thing passes the
173 # target type constraint.
175 return $target->check($thing);
178 return $class->$orig(%args);
181 =head2 C<coerce $thing>
183 Tries to coerce C<$thing> by first loading a class that might contain a type coercion for it.
187 around 'coerce' => sub {
188 my ($orig, $tc, $thing) = @_;
190 # The original coerce gets an hold onto the type coercions *before* calling
191 # the constraint. Thus, we have to force the loading before recalling into
194 # First, check whether $thing is already of the right kind.
195 return $thing if $tc->check($thing);
197 # If $thing isn't even an object, don't bother trying to autoload a coercion
198 my $class = blessed($thing);
199 if (defined $class) {
200 $class = $tc->mapper->($tc, $class);
202 if (defined $class) {
203 # Find the file to autoload
204 (my $pm = $class) =~ s{::}{/}g;
207 unless ($INC{$pm}) { # Not loaded yet
210 # We die often here, even though we're not really interested in the error.
211 # However, if a die handler is set (e.g. to \&Carp::confess), this can get
212 # very slow. Resetting the handler shows a 10% total time improvement for
224 __PACKAGE__->meta->make_immutable(
225 inline_constructor => 0,
230 L<Mouse::Meta::TypeConstraint>.
234 Vincent Pit, C<< <perl at profvince.com> >>, L<http://www.profvince.com>.
236 You can contact me by mail or on C<irc.perl.org> (vincent).
240 Please report any bugs or feature requests to C<bug-latex-tikz at rt.cpan.org>, or through the web interface at L<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=LaTeX-TikZ>.
241 I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
245 You can find documentation for this module with the perldoc command.
249 =head1 COPYRIGHT & LICENSE
251 Copyright 2010,2011,2012,2013,2014,2015 Vincent Pit, all rights reserved.
253 This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
257 1; # End of LaTeX::TikZ::Meta::TypeConstraint::Autocoerce