I've been learning Moose and I came across unexpected behavior: method modifiers (such as 'after') do not seem to work with attribute triggers. This is an issue because I want a subclass to extend a method that is defined as a trigger in the parent. The issue and one workaround is shown below.
use strict;
use warnings;
package Foo;
use Moose;
has 'attrib' => ( is => 'rw', trigger => \&attrib_changed );
has 'workaround' => ( is => 'rw', trigger => \&workaround_changed );
sub attrib_changed
{
print " in attrib_changed\n"; # called
}
after 'attrib_changed' => sub
{
print " in 'after' attrib_changed\n"; # not called
};
sub workaround_changed
{
my ( $self ) = @_;
print " in workaround_changed\n"; # called
$self->not_a_trigger;
}
after 'workaround_changed' => sub
{
print " in 'after' workaround_changed\n"; # not called
};
sub not_a_trigger
{
print " in not_a_trigger\n"; # called
}
after 'not_a_trigger' => sub
{
print " in 'after' not_a_trigger\n"; # called
};
my $foo = Foo->new;
print "Calling attrib( 1 ):\n";
$foo->attrib( 1 );
print "Calling workaround( 1 ):\n";
$foo->workaround( 1 );
Output:
Calling attrib( 1 ):
in attrib_changed
Calling workaround( 1 ):
in workaround_changed
in not_a_trigger
in 'after' not_a_trigger
I could not find anything in the Moose docs or online that documents this behavior as a known limitation. I'd be surprised if I were the first one to notice it, so it makes me wonder whether I am trying to do something that is best done some other way. Thoughts?
TIA
Update: Cross-posted to moose@perl.org