----- Original Message ----
> From: Jesse Luehrs <d...@tozt.net>
> > package Thing;
> > use Moose;
> > with (
> > DoesRobot => { excludes => 'draw', aliases => { draw => 'draw_with_arm'
> > },
> > 'DoesDrawable'
> > );
>
> Again, if the robot was a delegate rather than a role, you'd have
> $thing->draw_with_arm delegated to $thing->robot_arm->draw, but
> $thing->robot_arm->draw would still be available to be called
> separately:
>
> package Thing;
> use Moose;
> with 'DoesDrawable';
>
> has robot_arm => (
> is => 'ro',
> isa => 'RobotArm',
> default => { RobotArm->new },
> handles => { draw_with_arm => 'draw' },
> );
I've been trying to write up a response to this and I note that the delegation
example isn't equivalent. Consider the following code:
#!/usr/bin/perl
{
package RobotArm;
use Moose;
use Data::Dumper;
sub draw { print STDERR Dumper( \...@_ ); }
}
{
package Thing;
use Moose;
has robot_arm => (
is => 'ro',
isa => 'RobotArm',
default => sub { RobotArm->new },
handles => { draw_with_arm => 'draw' },
);
}
my $thing = Thing->new;
$thing->draw_with_arm;
That will print out:
$VAR1 = [
bless( {}, 'RobotArm' )
];
In short, the robot arm doesn't know what to draw because the original invocant
is not passed. How is this handled in Moose? I assume it's a matter of
somehow passing the invocant to the default?
Cheers,
Ovid
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