I intend to publish a few roles as a specification for third party support modules, e.g.:

package ModuleSpec;
use Moose::Role;
requires 
  'foo',
  'bar',
  'baz',
  ...
  ...;
# actually there are quite a lot of methods to require

The existence of module spec helps when developing a support module, by reminding developer what methods it should support.

However, in future releases I intend to incrementally update the spec by adding more methods. Yes, I know about API freezing and stable interface, but in my case the module spec is somewhat looser/less formal than an API specification, and most of the evolution will be new methods without affecting much of the old/existing methods.

I don't want third party developers to have to keep updating their modules whenever my module specification comes out and adds some new methods here and there. I want users to be able to use older support modules with the newer module specification role.

But I also like to keep this specification as a role to remind developers what methods are newly required, so they can update their module to reflect the new specification.

So, can I somehow make so that:

use AcmeSupportModule;
use Moose;
with 'ModuleSpec';
sub foo { ... }
sub bar { ... }
sub baz { ... }
...

when a method is missing/unimplemented, just emit a warning instead of failing to load the module.

Currently I wrap all 'requires' in ModuleSpec like this:

package ModuleSpec;
use Moose::Role;
use MyUtil;
apifunc 'foo', ...;
apifunc 'bar', ...;
apifunc 'baz', ...;
...

and, depending on the situation, apifunc() will eval a 'requires "foo"' or just 'sub foo { ... }'.

Any better way to do what I wish with less hackery?

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