So, Ovid has a new Moose related post on his use.perl journal (http://use.perl.org/~Ovid/journal/38809
) which sparked a discussion on #moose IRC channel.
The core of Ovid's issue is that when a role is composed into a class,
the class wins in any method conflicts. This is how roles were
originally specced in the traits paper and how they have always worked
(at least every time I wrote them). However Ovid makes a good point
that in overriding the role method "silently" it can make for some
very hard to debugging.
So, while I am not willing to change this behavior, I am willing to
add a warning so that it is not so "silent" anymore. So code like this
will warn you that your overriding a class method.
package Foo::Role;
use Moose::Role;
sub foo { ... }
package Foo::Class;
use Moose;
with 'Foo::Role';
sub foo { ... }
You will be able to silence this warning by explicitly excluding the
method from the role, like so:
package Foo::Role;
use Moose::Role;
sub foo { ... }
package Foo::Class;
use Moose;
with 'Foo::Role' => { excludes => 'foo' }; # excludes => [ 'foo' ]
also works if you have more then one method
sub foo { ... }
This should not only help with debugging, but also in refactoring
because it will be able to catch possibly unintended issues before
they become problems. This change is 100% backwards compat, but if you
don't want warnings you will have to be more explicit.
Any comments, questions, issues?
- Stevan
