Re: Using attributes for 'requires'

so far the best hack is :

sub location;
has location => (...);



On Sun, Jan 18, 2009 at 3:40 AM, Paul Fenwick <[email protected]> wrote:
> G'day Moosers,
>
> I'm currently working on some quick lightning talks demonstrating Moose and
> why it's useful.  One of the examples I'm using for roles looks like this:
>
>        package SunSmart;
>
>        use Moose::Role;
>        use Weather::Google;
>
>        use constant HOT => 28;         # Deg C.
>
>        requires 'go_outside';
>        requires 'location';
>
>        before 'go_outside' => sub {
>            my ($self) = @_;
>
>            my $weather = Weather::Google->new(
>                $self->location
>            );
>
>           if ($weather->current->{temp_c} > HOT) {
>              print "Don't forget your hat!\n";
>           }
>        }
>
> In short, if something has a location, and the ability to go_outside, then
> we can give it the SunSmart role, and it won't forget its hat if it's too hot.
>
> Unfortunately for me, `location` is an attribute on practically all of my
> classes, and Moose doesn't seem to like having an attribute to satisfy a
> 'requires':
>
>        'SunSmart' requires the method 'location' to be implemented by
>        'Person::Social'but the method is only an attribute accessor at
>        /usr/lib/perl5/site_perl/5.8/Moose/Meta/Role/Application.pm line 59
>
> This makes me sad, since I really *do* require a location method, but it's
> absolutely fine if it's an attribute.
>
> I know there have been some discussions about this in the past, with the
> possibility of a 'requires_attr' or similar keyword, although to the best of
> my knowledge this is not yet implemented.
>
> In the meantime, is there any easy[1] way to tell Moose that attributes are
> just fine to satisify 'requires' dependencies?
>
> Many thanks,
>
>        Paul
>
> [1] Since I'm writing short talks for mixed audiences, I can't show anything
> too scary.  Sure, I'm willing to dig around in the guts of all sorts of
> things, but I'm trying to dispel the myth that as a regular Perl programmer
> you should have to.
>
> --
> Paul Fenwick <[email protected]> | http://perltraining.com.au/
> Director of Training                   | Ph:  +61 3 9354 6001
> Perl Training Australia                | Fax: +61 3 9354 2681
>
>



-- 
benh~

http://three.sentenc.es/