my $bar = sub { # do something here };
$bar->(); # executes the stuff in the anonymous sub above

##</code><code>##

sub foo {
     # do something here
}

my $bar = \&foo;
$bar->(); #executes the stuff in foo()

##</code><code>##

my %actions = (
     foo => \&do_foo, # some long operation
     bar => sub { # some short one line thing },
     default => sub { # do something by default },
);

my $request = $cgi->param('request');
if( exists($actions{ $request } )) {
     $actions{ $request }->();
}
else {
     $actions{ default }->();
}