use strict;
use warnings;
use feature 'say';

package Foo {
sub new { my $pkg = shift; return bless {}, $pkg }
sub frob { my $self = shift; $self-> foo( \&cb ) }
sub blurt { my $self = shift; $self-> foo( 'cb' ) }
sub foo { my ( $self, $cb ) = @_; $self-> $cb }
sub cb { my $self = shift; say ref $self, ' ', __PACKAGE__ }
};

package Bar {
our @ISA = ( 'Foo' );
sub cb { my $self = shift; say ref $self, ' ', __PACKAGE__ }
};

my $foo = Foo-> new;
my $bar = Bar-> new;

$foo-> frob;
$bar-> frob;
$foo-> blurt;
$bar-> blurt;

[download]

It says (which doesn't require explanation, that's not the question):

Foo Foo
Bar Foo
Foo Foo
Bar Bar

[download]

The callbacks in above classes look the same for the SSCCE, but let's pretend they are different, and I only want to change callback behaviour in derived class.

In practice, there are multiple changes, including some of the "callbacks". My class inherits from CAM::PDF, one of its "cornerstones" is the traverse method, which is called by a few specialized methods with a callback as an argument. e.g., verbatim, a short one:

sub setObjNum
{
   my $self = shift;
   my $objnode = shift;
   my $objnum = shift;
   my $gennum = shift;
 
   $self->traverse(0, $objnode, \&_setObjNumCB, [$objnum, $gennum]);
   return;
}

[download]
and relevant line in traverse is: 
$self->$func($objnode, $funcdata);

[download]

Is calling a callback i.e. code reference as method on an instance the accepted and OK practice, to begin with? In derived class, I'm now in some mess of a situation.

Should I override every "specialized" method (even those I didn't intend to) and replace coderefs with strings? Will it hurt performance, and how much?

Maybe I can fix all that at the "central location" (i.e. traverse) without touching every "specialized method" -- to convert a coderef to sub name? How to do that using Perl built-in (or core) functions? Would this solution be better (faster, cleaner, etc.)?

In reply to Methods, within a class, pass callbacks; how to deal with that in derived class? by Anonymous Monk

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