Provided by: libparse-method-signatures-perl_1.003019-1_all bug


       Parse::Method::Signatures - Perl6 like method signature parser


       Inspired by Perl6::Signature but streamlined to just support the subset deemed useful for
       TryCatch and MooseX::Method::Signatures.


       ·   Document the parameter return types.

       ·   Probably lots of other things


       There are only two public methods to this module, both of which should be called as class
       methods. Both methods accept  either a single (non-ref) scalar as the value for the
       "input" attribute, or normal new style arguments (hash or hash-ref).

        my $sig = Parse::Method::Signatures->signature( '(Str $foo)' )

       Attempts to parse the (bracketed) method signature. Returns a value or croaks on error.

         my $param = Parse::Method::Signatures->param( 'Str $foo where { length($_) < 10 }')

       Attempts to parse the specification for a single parameter. Returns value or croaks on


       All the attributes on this class are read-only.

       Type: Str

       The string to parse.

       Type: Int

       Offset into "input" at which to start parsing. Useful for using with Devel::Declare

       Default: Parse::Method::Signatures::Sig

       Type: Str (loaded on demand class name)

       Default: Parse::Method::Signatures::Param

       Type: Str (loaded on demand class name)

       Default: Parse::Method::Signatures::TypeConstraint

       Type: Str (loaded on demand class name)

       Class that is used to turn the parsed type constraint into an actual
       Moose::Meta::TypeConstraint object.

       Type: ClassName

       Let this module know which package it is parsing signatures form. This is entirely
       optional, and the only effect is has is on parsing type constraints.

       If this attribute is set it is passed to "type_constraint_class" which can use it to
       introspect the package (commonly for MooseX::Types exported types). See
       "find_registered_constraint" in Parse::Method::Signature::TypeConstraints for more

       Type: CodeRef

       Passed to the constructor of "type_constraint_class". Default implementation of this
       callback asks Moose for a type constrain matching the name passed in.  If you have more
       complex requirements, such as parsing types created by MooseX::Types then you will want a
       callback similar to this:

        # my $target_package defined elsewhere.
        my $tc_cb = sub {
          my ($pms_tc, $name) = @_;
          my $code = $target_package->can($name);
          $code ? eval { $code->() }
                : $pms_tc->find_registered_constraint($name);

       Note that the above example is better provided by providing the "from_namespace"


       Like Perl6::Signature, the parsing of certain constructs is currently only a 'best effort'
       - specifically default values and where code blocks might not successfully for certain
       complex cases. Patches/Failing tests welcome.

       Additionally, default value specifications are not evaluated which means that no such
       lexical or similar errors will not be produced by this module.  Constant folding will also
       not be performed.

       There are certain constructs that are simply too much hassle to avoid when the work around
       is simple. Currently the only cases that are known to parse wrong are when using anonymous
       variables (i.e. just sigils) in unpacked arrays. Take the following example:

        method foo (ArrayRef [$, $], $some_value_we_care_about) {

       In this case the $] is treated as one of perl's magic variables (specifically, the patch
       level of the Perl interpreter) rather than a "$" followed by a "]" as was almost certainly
       intended. The work around for this is simple: introduce a space between the characters:

        method foo (ArrayRef [ $, $ ], $some_value_we_care_about) {

       The same applies


       Ash Berlin <>.

       Thanks to Florian Ragwitz <>.

       Many thanks to Piers Cawley to showing me the way to refactor my spaghetti code into
       something more manageable.


       Devel::Declare which is used by most modules that use this (currently by all modules known
       to the author.)



       Licensed under the same terms as Perl itself.

       This distribution copyright 2008-2009, Ash Berlin <>