#!/usr/bin/perl -wT
use strict;

# hash key lookup using the actual hash (no reference)
my %foo = (bar => 'data');
my $val = $foo{bar};      # fetch the scalar key (hence the '$' infront of foo) from the hash
print "Val  => $val\n";

# hash key lookup using a referent to the hash (hard reference)
my %hash = (bar => 'data2');
my $foo = \%hash;
my $val2 = $foo->{bar};   # can also be written '$$foo{bar}';
print "Val2 => $val2\n";

# using symbolic (soft) references
use vars qw($foo $bar);
$bar = 'data3';
$foo = 'bar';
my $val3;
{
  no strict 'refs';     # 'use strict' won't allow this
  $val3 = $$foo;        # find the data by treating the value of $foo as a var name
}
print "Val3 => $val3\n";

=output
Val  => data
Val2 => data2
Val3 => data3