#!/usr/bin/env perl    

use strict;
use warnings;
use 5.010;

my $hash = { key => ' value1 '.get_value2()};

say $hash->{key};
say $hash->{key};
say $hash->{key};

$hash = { key => ' value2 '.get_value2()};

say $hash->{key};
say $hash->{key};
say $hash->{key};

sub get_value2 {
  return rand();
}

##</code><code>##

 value1 0.557144237523065
 value1 0.557144237523065
 value1 0.557144237523065
 value2 0.0543176085661514
 value2 0.0543176085661514
 value2 0.0543176085661514