use Perl

• parameterized roles (Score:1)

  by hdp (1658) on 2009.03.18 23:15 (#67861) Journal

  Moving along, were I to eliminate base classes, that would also eliminate this silliness:

          sub foo {
                  my $proto = shift;
                  my $class = ref $proto || $proto;
                  die "You must override 'foo' in $class";
          }

  That fires at runtime, not compile time. Just adding a requires qw'foo'; to your role and this becomes a compile-time failure.

  Alternately, if the "foo" you're overriding there is (as it so often is) something like this:
  
sub foo_plugins {
    return ("My::Foo", "External::Library::Foo");
}

  MooseX::Role::Parameterized [cpan.org] might be a good option. e.g.
  
use MyRole => { foo_plugins => ["My::Foo", "External::Library::Foo" ] };

  # elsewhere...
package MyRole;
use MooseX::Role::Parameterized;
parameter foo_plugins => (
    isa => 'ArrayRef[ClassName]',
    required => 1,
);
role {
    my $p = shift;
    method munge_stuff => sub {
        # do something for each @{$p->foo_plugins}
    };
};


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