use strict;
sub test { print 'hello world!' }; 
my %hash;
$hash{test} = \&test; 

# This generates an error:
&$hash{test};
# Global symbol "$hash" requires explicit package name at script.pl line 7.
# syntax error at script.pl line 7, near "$hash{test"
# Execution of script.pl aborted due to compilation errors.

# But this works:
&{$hash{test}};

# why???