Parameterizable
NAME
Parameterizable - Make a class parameterizable
SYNOPSIS
use Parameterizable;
role Fooey[::Type] {
method of() { Type }
}
class Foo is Parameterizable {
method MIXIN(Mu:U \type) { Fooey[type] }
}
my $obj = Foo[Int].new;
say $obj.of; # OUTPUT: Ā«(Int)ā¤Ā»DESCRIPTION
class Parameterizable is Mu {}Roles can be parameterized, and in almost all cases such a role can be used as if it were a class because Raku supports automatic role punning. One unsupported use case is a method that assigns to the invocant, for example to support autovivification. If a type wants to support that, it must be a class. But classes are not parameterizable... or are they?
Class Parameterizable uses an undocumented Rakudo feature that allows classes to be parameterized. To support parameterization, a class may simply inherit from Parameterizable and define a method MIXIN that maps positional arguments to a role definition. The class can then be parameterized with arguments that are accepted by a .MIXIN candidate.
Class parameterization works by mixing in the role returned by .MIXIN. The parameterized class is given a name that includes the types of arguments it was parameterized with.
SEE ALSO
AUTHOR
Peter du Marchie van Voorthuysen
Source can be located at: https://github.com/dumarchie/raku-parameterizable
COPYRIGHT AND LICENSE
Copyright 2022 Peter du Marchie van Voorthuysen
This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.