Thanks, but I'm not sure I follow. The documentation doesn't mention using Moose::Util::TypeConstraints. What, exactly, does the code in the documentation do?</code>

Moose::Util::TypeConstraints isn't really important here and I should have edited it out of the snippet. The important thing to understand is

package Foo::Bar;
use Moose::Role;
 
requires 'foo';
requires 'bar';
[download]

i.e. required methods. This is how a role indicates that a class consuming it should have some extra behaviour that the role depends on. Taking this to an extreme you can even have a role that only has required method specifiers - this gives you something similar to the interface construct found in Java/C#/PHP.

And this latter type of role is what is intended to be used when you specify a role to the 'handles' clause.

Does that make sense?

In the documentation, it's made to look like you can extend or override methods provided by URI but from what I can tell it does nothing of the sort. Take this, for example, which emulates what is in the documentation:

{
  package MyURIRole 0.000001;

  use Moose::Role;

  requires 'host';
  requires 'path';

  sub print_hi {
    my $s = shift;
    print "hi\n";
  }
}

{ 
  package MyURI 0.000001;

  use Carp;
  use Moose;
  use URI;

  has 'uri' => ( is => 'ro', isa => 'URI', handles => 'MyURIRole', );

}

#! /usr/bin/env perl
use MyURI;

use strict;
use warnings;

my $uri = MyURI->new( uri => URI->new('http://www.perl.com/the_path'))
+;
print $uri->host;
print "\n";
print $uri->path;
print "\n";
$uri->print_hi;
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From the documentation's explanation, I would expect the $uri->print_hi to print out "hi". Instead, I get an error:

Can't locate object method "print_hi" via package "URI::http" at inline delegation in MyURI for uri->print_hi (attribute declared in MyURI.pm at line 7) line 18.

So I'm not sure why the documentation is suggesting that using a role name with handles is a good way to delegate when using another package like URI. What is to be gained from it? Am I missing something?

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