NAME

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

SYNOPSIS

    package Foo;

    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.

DISCLAIMER

This is ALPHA SOFTWARE. Use at your own risk. Features may change.

DESCRIPTION

Provides a proper method keyword, like "sub" but specificly 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)

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 "affe"
    # $baz is named, required, must be an integer, defaults to 42 and needs
    #      to be even and greater than 10

BUGS, CAVEATS AND NOTES

Non-scalar parameters

Currently parameters that aren't scalars are unsupported. This is going to change soon.

Fancy signatures

Perl6::Signature is used to parse the signatures. However, some signatures that can be parsed by it aren't supported by this module (yet).

Debugging

This totally breaks the debugger. Will have to wait on Devel::Declare fixes.

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 surprisnigly stable.

What about regular subroutines?

Devel::Declare cannot yet change the way sub behaves.

What about the return value?

Currently there is no support for types or declaring the type of the return value.

SEE ALSO

Method::Signatures

MooseX::Method

Perl6::Subs

Devel::Declare

Perl6::Signature

Moose

COPYRIGHT AND LICENSE

Copyright (c) 2008 Florian Ragwitz

Code based on the tests for Devel::Declare.

Documentation based on MooseX::Method and Method::Signatures.

Licensed under the same terms as Perl itself.

AUTHOR

Florian Ragwitz <rafl@debian.org>

cpanm MooseX::Method::Signatures

perl -MCPAN -e shell
install MooseX::Method::Signatures