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 );
[download]

Output:

Calling attrib( 1 ):
  in attrib_changed
Calling workaround( 1 ):
  in workaround_changed
  in not_a_trigger
    in 'after' not_a_trigger
[download]

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

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