Re: HASH value as a subroutine call

[Perlbotics]

You need to populate the hash with code-references (\&sub).

Try:

use strict;

# my $code_ref = {'SUM', 'sum'};  
  my $code_ref = {'SUM', \&sum};

sub sum($$){...}   # do you really need ($$) ? That is rarely useful. 

# ($codes->{'SUM'})->(4,5);   # $codes? You mean $code_ref?
$code_ref->{'SUM'}->(4,5);

[AnomalousMonk]

sub sum($$){...}   # do you really need ($$) ? That is rarely useful.

Rarely useful, often misused, and in this case (in which prototypes are not checked at all) totally useless. E.g.:

>perl -wMstrict -le
"sub sum ($$);
 ;;
 my $codes = { 'SOFT' => 'sum',  'HARD' => \&sum, };
 ;;
 $codes->{HARD}->('HARD', 1, 2, 3, 4);
 ;;
 {
 no strict 'refs';
 $codes->{SOFT}->('SOFT', 9, 8, 7, 6);
 }
 ;;
 sub sum ($$) { print qq{(@_)  arguments: }, scalar @_; }
"
(HARD 1 2 3 4)  arguments: 5
(SOFT 9 8 7 6)  arguments: 5