Thus saith btrott:

sub cant_do_that { 
        my $self = shift; 
        print "Error: Use of undefined Abstract Method by $self.\n"; 
    } 
 
    use subs qw/methodOne methodTwo/; 
    *methodOne = \&cant_do_that; 
    *methodTwo = \&cant_do_that;
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I'd simplify the whole lot of that by doing what use subs does directly:

BEGIN {
  for my $fakir (qw(methodOne methodTwo)) {
    *$fakir = sub { die "undef abstract method $fakir used by ".(shift
+); }
  }
}
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No fuss, no muss, and you even get a distinguishing mark.

-- Randal L. Schwartz, Perl hacker