X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FMooseX%2FTypes%2FUtil.pm;h=ea2c35c7e97f7791abe71cc337f79817c6f2a742;hb=e9dc30af81ed775a6ac0a0f0c1daad021e5569f6;hp=5bd5bcf8fb7b58773ecf798c8b3f884e448641f7;hpb=52d358e2cf004a8b632b655832f7e9101db3c4dc;p=gitmo%2FMooseX-Types.git

diff --git a/lib/MooseX/Types/Util.pm b/lib/MooseX/Types/Util.pm
index 5bd5bcf..ea2c35c 100644
--- a/lib/MooseX/Types/Util.pm
+++ b/lib/MooseX/Types/Util.pm
@@ -1,24 +1,21 @@
 package MooseX::Types::Util;
 
-=head1 NAME
-
-MooseX::Types::Util - Common utility functions for the module
-
-=cut
+#ABSTRACT: Common utility functions for the distribution
 
 use warnings;
 use strict;
+use Scalar::Util 'blessed';
 
 use base 'Exporter';
 
 =head1 DESCRIPTION
 
-This package the exportable functions that many parts in 
+This package the exportable functions that many parts in
 L<MooseX::Types> might need.
 
 =cut
 
-our @EXPORT_OK = qw( filter_tags );
+our @EXPORT_OK = qw( filter_tags has_available_type_export );
 
 =head1 FUNCTIONS
 
@@ -43,14 +40,59 @@ sub filter_tags {
     return \%tags, \@other;
 }
 
-=head1 SEE ALSO
+=head2 has_available_type_export
 
-L<MooseX::Types::Moose>, L<Exporter>
+  TypeConstraint | Undef = has_available_type_export($package, $name);
+
+This function allows you to introspect if a given type export is available
+I<at this point in time>. This means that the C<$package> must have imported
+a typeconstraint with the name C<$name>, and it must be still in its symbol
+table.
+
+Two arguments are expected:
+
+=over 4
+
+=item $package
+
+The name of the package to introspect.
+
+=item $name
+
+The name of the type export to introspect.
+
+=back
+
+B<Note> that the C<$name> is the I<exported> name of the type, not the declared
+one. This means that if you use L<Sub::Exporter>s functionality to rename an import
+like this:
 
-=head1 AUTHOR AND COPYRIGHT
+  use MyTypes Str => { -as => 'MyStr' };
 
-Robert 'phaylon' Sedlacek C<E<lt>rs@474.atE<gt>>, with many thanks to
-the C<#moose> cabal on C<irc.perl.org>.
+you would have to introspect this type like this:
+
+  has_available_type_export $package, 'MyStr';
+
+The return value will be either the type constraint that belongs to the export
+or an undefined value.
+
+=cut
+
+sub has_available_type_export {
+    my ($package, $name) = @_;
+
+    my $sub = $package->can($name)
+        or return undef;
+
+    return undef
+        unless blessed $sub && $sub->isa('MooseX::Types::EXPORTED_TYPE_CONSTRAINT');
+
+    return $sub->();
+}
+
+=head1 SEE ALSO
+
+L<MooseX::Types::Moose>, L<Exporter>
 
 =head1 LICENSE