Really? It shouldn't.

use strict;
use warnings;

my %op = (
  'toupper' => \*uc{CODE},
  #...
);


print( $op{toupper}->('foo'), "\n" );
[download]

Name "main::uc" used only once: possible typo at a.pl line 5.
Not a CODE reference at a.pl line 10.
[download]

Originally posted as a Categorized Answer.