How can I delegate to a sub object of an object with Moose handles?

Question

The Moose documentation says that I can delegate to the object thing easily enough.

has 'thing' => (
   ...
   handles => { set_foo => [ set => 'foo' ] },
);

# $self->set_foo(...) calls $self->thing->set('foo', ...)

But I really want to delegate to an object on thing, specifically a datetime object

has 'thing' => (
   ...
   handles => {
       get_month => { datetime ... },
   },
);

# $self->get_month calls $self->thing->datetime->month;

how would I have to construct handles to get it to do this?

ikegami · Accepted Answer · 2012-05-14T14:58:51.307

3

has thing => (
   ...
   handles => {
      get_month => sub { $_[0]->thing->datetime->month },
   },
);

Short of adding datetime_month to thing, you'll have to write your own delegator.

edited May 14 '12 at 14:58

answered May 14 '12 at 02:59

ikegami

1

At this point you're already writing the method yourself and could as well drop the `handles` declaration and just write `sub get_month` manually. – rafl May 14 '12 at 07:41
@rafl, You could do that, but I disagree about it being better to move it out. Specifically, writing it as a delegator conveys information to the reader that you wouldn't get otherwise. – ikegami May 14 '12 at 16:57
I also have other handles on the same object that didn't require this level of depth... so it kind of puts them all in the same spot. – xenoterracide May 14 '12 at 20:48
IMO would have been nice to more declaratively delegate to infinite object methods. maybe `method => { method => { method => [ params ] } } }` – xenoterracide May 14 '12 at 20:51
@xenoterracide, That's positively awful. Not only does the params bit breaks the model, it does so in a very inconsistent and very limiting way (i.e. only applies to the inner layer). – ikegami May 15 '12 at 01:17
Furthermore, `sub { $_[0]->thing->datetime->get_month }` is *way* more readable than `{ datetime => { month => { get_month => [] } } }` – ikegami May 15 '12 at 01:21

1 Answers1