Страницы справочника OS X

Эта страница руководства для  версии 10.9 Mac OS X

Читать страницы руководства

MooseX::Method::Signatures(3)        User Contributed Perl Documentation       MooseX::Method::Signatures(3)



NAME
       MooseX::Method::Signatures - Method declarations with type constraints and no source filter

SYNOPSIS
           package Foo;

           use Moose;
           use MooseX::Method::Signatures;

           method morning (Str $name) {
               $self->say("Good morning ${name}!");
           }

           method hello (Str :$who, Int :$age where { $_ > 0 }) {
               $self->say("Hello ${who}, I am ${age} years old!");
           }

           method greet (Str $name, Bool :$excited = 0) {
               if ($excited) {
                   $self->say("GREETINGS ${name}!");
               }
               else {
                   $self->say("Hi ${name}!");
               }
           }

           $foo->morning('Resi');                          # This works.

           $foo->hello(who => 'world', age => 42);         # This too.

           $foo->greet('Resi', excited => 1);              # And this as well.

           $foo->hello(who => 'world', age => 'fortytwo'); # This doesn't.

           $foo->hello(who => 'world', age => -23);        # This neither.

           $foo->morning;                                  # Won't work.

           $foo->greet;                                    # Will fail.

DESCRIPTION
       Provides a proper method keyword, like "sub" but specifically for making methods and validating their
       arguments against Moose type constraints.

SIGNATURE SYNTAX
       The signature syntax is heavily based on Perl 6. However not the full Perl 6 signature syntax is
       supported yet and some of it never will be.

   Type Constraints
           method foo (             $affe) # no type checking
           method bar (Animal       $affe) # $affe->isa('Animal')
           method baz (Animal|Human $affe) # $affe->isa('Animal') || $affe->isa('Human')

   Positional vs. Named
           method foo ( $a,  $b,  $c) # positional
           method bar (:$a, :$b, :$c) # named
           method baz ( $a,  $b, :$c) # combined

   Required vs. Optional
           method foo ($a , $b!, :$c!, :$d!) # required
           method bar ($a?, $b?, :$c , :$d?) # optional

   Defaults
           method foo ($a = 42) # defaults to 42

   Constraints
           method foo ($foo where { $_ % 2 == 0 }) # only even

   Invocant
           method foo (        $moo) # invocant is called $self and is required
           method bar ($self:  $moo) # same, but explicit
           method baz ($class: $moo) # invocant is called $class

   Labels
           method foo (:     $affe ) # called as $obj->foo(affe => $value)
           method bar (:apan($affe)) # called as $obj->foo(apan => $value)

   Traits
           method foo (Affe $bar does trait)
           method foo (Affe $bar is trait)

       The only currently supported trait is "coerce", which will attempt to coerce the value provided if it
       doesn't satisfy the requirements of the type constraint.

   Placeholders
           method foo ($bar, $, $baz)

       Sometimes you don't care about some params you're being called with. Just put the bare sigil instead
       of a full variable name into the signature to avoid an extra lexical variable to be created.

   Complex Example
           method foo ( SomeClass $thing where { $_->can('stuff') }:
                        Str  $bar  = "apan",
                        Int :$baz! = 42 where { $_ % 2 == 0 } where { $_ > 10 } )

           # the invocant is called $thing, must be an instance of SomeClass and
                  has to implement a 'stuff' method
           # $bar is positional, required, must be a string and defaults to "apan"
           # $baz is named, required, must be an integer, defaults to 42 and needs
           #      to be even and greater than 10

BUGS, CAVEATS AND NOTES
       This module is as stable now, but this is not to say that it is entirely bug free. If you notice any
       odd behaviour (messages not being as good as they could for example) then please raise a bug.

   Fancy signatures
       Parse::Method::Signatures is used to parse the signatures. However, some signatures that can be
       parsed by it aren't supported by this module (yet).

   No source filter
       While this module does rely on the hairy black magic of Devel::Declare it does not depend on a source
       filter. As such, it doesn't try to parse and rewrite your source code and there should be no weird
       side effects.

       Devel::Declare only effects compilation. After that, it's a normal subroutine.  As such, for all that
       hairy magic, this module is surprisingly stable.

   What about regular subroutines?
       Devel::Declare cannot yet change the way "sub" behaves. However, the signatures module can. Right now
       it only provides very basic signatures, but it's extendable enough that plugging
       MooseX::Method::Signatures signatures into that should be quite possible.

   What about the return value?
       Type constraints for return values can be declared using

         method foo (Int $x, Str $y) returns (Bool) { ... }

       however, this feature only works with scalar return values and is still considered to be
       experimental.

   Interaction with Moose::Role
       Methods not seen by a role's "requires"

       Because the processing of the MooseX::Method::Signatures "method" and the Moose "with" keywords are
       both done at runtime, it can happen that a role will require a method before it is declared (which
       will cause Moose to complain very loudly and abort the program).

       For example, the following will not work:

           # in file Canine.pm

           package Canine;

           use Moose;
           use MooseX::Method::Signatures;

           with 'Watchdog';

           method bark { print "Woof!\n"; }

           1;


           # in file Watchdog.pm

           package Watchdog;

           use Moose::Role;

           requires 'bark';  # will assert! evaluated before 'method' is processed

           sub warn_intruder {
               my $self = shift;
               my $intruder = shift;

               $self->bark until $intruder->gone;
           }

           1;

       A workaround for this problem is to use "with" only after the methods have been defined.  To take our
       previous example, Canine could be reworked thus:

           package Canine;

           use Moose;
           use MooseX::Method::Signatures;

           method bark { print "Woof!\n"; }

           with 'Watchdog';

           1;

       A better solution is to use MooseX::Declare instead of plain MooseX::Method::Signatures. It defers
       application of roles until the end of the class definition. With it, our example would becomes:

           # in file Canine.pm

           use MooseX::Declare;

           class Canine with Watchdog {
               method bark { print "Woof!\n"; }
           }

           1;

           # in file Watchdog.pm

           use MooseX::Declare;

           role Watchdog {
               requires 'bark';

               method warn_intruder ( $intruder ) {
                   $self->bark until $intruder->gone;
               }
           }

           1;

       Subroutine redefined warnings

       When composing a Moose::Role into a class that uses MooseX::Method::Signatures, you may get a
       "Subroutine redefined" warning. This happens when both the role and the class define a
       method/subroutine of the same name. (The way roles work, the one defined in the class takes
       precedence.) To eliminate this warning, make sure that your "with" declaration happens after any
       method/subroutine declarations that may have the same name as a method/subroutine within a role.

SEE ALSO
       MooseX::Declare

       Method::Signatures::Simple

       Method::Signatures

       Perl6::Subs

       Devel::Declare

       Parse::Method::Signatures

       Moose

AUTHORS
       •   Florian Ragwitz <rafl@debian.org>

       •   Ash Berlin <ash@cpan.org>

       •   Cory Watson <gphat@cpan.org>

       •   Daniel Ruoso <daniel@ruoso.com>

       •   Dave Rolsky <autarch@urth.org>

       •   Hakim Cassimally <hakim.cassimally@gmail.com>

       •   Jonathan Scott Duff <duff@pobox.com>

       •   Justin Hunter <justin.d.hunter@gmail.com>

       •   Kent Fredric <kentfredric@gmail.com>

       •   Maik Hentsche <maik.hentsche@amd.com>

       •   Matt Kraai <kraai@ftbfs.org>

       •   Rhesa Rozendaal <rhesa@cpan.org>

       •   Ricardo SIGNES <rjbs@cpan.org>

       •   Steffen Schwigon <ss5@renormalist.net>

       •   Yanick Champoux <yanick@babyl.dyndns.org>

       •   Nicholas Perez <nperez@cpan.org>

COPYRIGHT AND LICENSE
       This software is copyright (c) 2011 by Florian Ragwitz.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
       programming language system itself.



perl v5.12.5                                     2011-09-12                    MooseX::Method::Signatures(3)