#!perl
use strict;
use warnings;
use Data::Dumper; $Data::Dumper::Purity =1;

my %dispatch = (
    original_a => sub {print "AAA\n"},
);

$dispatch{a}=\&{$dispatch{original_a}};

print Dumper(\%dispatch);


##</code><code>##

Encountered CODE ref, using dummy placeholder at C:/Perl/lib/Data/Dumper.pm line 179.
$VAR1 = {
          'a' => sub { "DUMMY" },
          'original_a' => do{my $o}
        };
$VAR1->{'original_a'} = $VAR1->{'a'};


##</code><code>##

perl -MData::Dumper -e "$h{a} = sub{print qq(AAA\n)}; $h{alias} = \&{$h{a}}; print Dumper(\%h)"

$VAR1 = {
          'a' => sub { "DUMMY" },
          'alias' => $VAR1->{'a'}
        };