method as trigger

Hello,

I was trying to use a method of my class as 'trigger' in an attributes 
definition. Here is what I wrote:

has pub_in_a_TkObjectsModel_Instance => ( isa => 'TkObjectsModel',
                                           is  => 'rw',
                                       trigger => sub{$_[0] -> changed($_[2])},
                                      );

That works fine. However, are there more elegant solutions? Wouldn't it be a 
nice feature, if we could say:

...
trigger => 'changed',
...

(Like in a Perl-Tk callback definition)?

Christoph