TITLE

Metaobject that supports I<punning> of roles.


SUBTITLE

I<Warning>: this role is part of the Rakudo implementation, and is not
a part of the language specification.


Implements the ability to create objects from C<Role>s without the intermediate
need to use a class. Not intended to be used directly (will in fact error if
it's C<use>d), but via punning of roles, as below. This is also Rakudo specific
and not part of the spec.


code

root

Metaobject that can hold attributes


role Metamodel::AttributeContainer


Metaobject that supports the C3 method resolution order


role Metamodel::C3MRO


Metarole for documenting types.


role Metamodel::Documenting


Metaobject supporting object finalization


role Metamodel::Finalization


Metaobject that supports storing and introspecting methods


role Metamodel::MethodContainer


Metaobject for generating mixins


role Metamodel::Mixins


Metaobject that supports resolving inherited methods


role Metamodel::MROBasedMethodDispatch


Metaobject that supports multiple inheritance


role Metamodel::MultipleInheritance


Metaobject that supports named types


role Metamodel::Naming


Represents a group of roles with different parameterizations


role Metamodel::ParametricRoleGroupHOW


Represents a non-instantiated, parameterized, role.


role Metamodel::ParametricRoleHOW


Metaobject that supports private methods


role Metamodel::PrivateMethodContainer


Metaobject that supports holding/containing roles


role Metamodel::RoleContainer


Metarole for type stashes


role Metamodel::Stashing


Metaobject that supports trust relations between types


role Metamodel::Trusting


Metaobjects that support versioning


role Metamodel::Versioning


Metaobject that supports punning of roles.


para

L<Examples| file:../examples/index.podlite>


L<Download |file:../download/index.podlite>


React

=begin React :component<HeaderCol> :id<menu> 
=para L<Documentation|/doc/introduction>
=para L<Modules| /mods>
=para L<Examples| file:../examples/index.podlite>
=para L<Download |file:../download/index.podlite>
=para L<About|file:../about/index.podlite>
=para 🔍 K<⌘K>/K<ctrl-K>
=end React


HEADER

FOOTER

role Metamodel::RolePunning


Types may have a stash associated with them, which is a named hash
containing our-scoped symbols for that type's package. When this is
the case, they can be used like namespaces; you can get their stash
using their C<WHO> property or with the C<::> dispatch operator:


=begin code
module Nested {
    module Namespace {
        constant Symbol = $?MODULE;
    }
}

say Nested::Namespace::Symbol;         # OUTPUT: «(Namespace)␤»
say Nested.WHO<Namespace>.WHO<Symbol>; # OUTPUT: «(Namespace)␤»
=end code


C<Metamodel::Stashing> is the metarole that handles creating and
setting a stash object for types. Types used with this metarole are
expected to support naming, so when writing custom HOWs that do it,
ensure they also do L<C<Metamodel::Naming>|/type/Metamodel::Naming>.


head

Creates and sets a stash for a type, returning C<$type_obj>.


This method is typically called as the last step of creating a new
type. For example, this is how it would be used in a minimal HOW that
only supports naming and stashing:


=begin code :solo
class WithStashHOW
    does Metamodel::Naming
    does Metamodel::Stashing
{
    method new_type(WithStashHOW:_: Str:D :$name! --> Mu) {
        my WithStashHOW:D $meta := self.new;
        my Mu             $type := Metamodel::Primitives.create_type: $meta, 'Uninstantiable';
        $meta.set_name: $type, $name;
        self.add_stash: $type
    }
}

my Mu constant WithStash = WithStashHOW.new_type: :name<WithStash>;
say WithStash.WHO; # OUTPUT: «WithStash␤»
=end code


Implements the ability to hold roles to be held for composition.


Adds the C<$role> to the list of roles to be composed.


method roles_to_compose($obj --> List:D)


returns a list of roles added with C<add_role>, which are to be composed
at type composition time.


The Raku Knowledge Base


=begin React :component<HeaderCol> :id<footer>  
=begin nested :!nested
=item1 B<Language>
    =item2 L<Get started|file:../getting-started/getting-started.podlite>
    =item2 L<Why Raku?|/doc/language/faq#Why-should-I-learn-Raku-What's-so-great-about-it>
    =item2 L<Try Raku|https://glot.io/new/raku>
    =item2 L<Raku cheat sheet|https://github.com/Raku/mu/blob/master/docs/Perl6/Cheatsheet/cheatsheet.txt>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<Raku on Exercism|https://exercism.org/tracks/raku>
    =item2 L<Wikipedia|https://en.wikipedia.org/wiki/Raku_(programming_language)>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>

=end nested
=begin nested :!nested

=item1 B<L<Documentation|/doc>>
    =item2 L<Getting started, Migration guides from other languages, & Tutorials | file:../doc/introduction.podlite>
    =item2 L<Language References|file:../doc/reference.podlite>
    =item2 L<Type Reference| file:../doc/types.podlite>
    =item2 L<Miscellaneous| file:../doc/miscellaneous.podlite>
    =item2 L<FAQs (Frequently Asked Questions)|/doc/language/faq>
    =item2 L<Community|/doc/language/community>
    =item2 L<The list of all documents|file:../doc/index.podlite>

=item1 B<Resources>
    =item2 L<The Raku Guide|https://raku.guide/>
    =item2 L<Books |https://perl6book.com/>
    =item2 L<Rosetta Code | https://www.raku.org/community/rosettacode>

=end nested
=begin nested :!nested

=item1 B<Resoures>
    =item2 L<Download | file:../download/index.podlite>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>

=item1 B<Learning>
    =item2 L<The Raku Guide|https://raku.guide/>
    =item2 L<Wikibook |https://en.wikibooks.org/wiki/Raku_Programming>
    =item2 L<Books |https://perl6book.com/>
    =item2 L<Rosetta Code | https://www.raku.org/community/rosettacode>
    =item2 L<Learn Raku in Y minutes|https://learnxinyminutes.com/docs/raku/>
    =item2 L<Golfing |https://github.com/AlexDaniel/raku-golf-cheatsheet>
=end nested
=begin nested :!nested

=item1 B<Explore>
    =item2 L<Raku Blog Aggregator|https://planet.raku.org/>
    =item2 L<Rakudo Weekly|https://rakudoweekly.blog/>
    =item2 L<The Weekly Challenge |https://perlweeklychallenge.org/>
    =item2 L<Raku Advent Calendar|https://raku-advent.blog/>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>

=end nested
=end React


=begin React :component<CookieConsent> :id<CookieConsent> :buttonCaption("Got it!")
=para
This website uses cookies for analytics.
=end React


See Also