use CGI;
use vars qw(%Actions);
%Actions = (
  eins => { code => \&Action1, template => 'action1.tmpl', x => 20 },
  zwei => { code => \&Action2, template => 'action2.tmpl', a => 30 },
  drei => { code => \&Action3, template => 'action3.tmpl', foo => 'bar' },
  default => { code => \&Start, template => 'start.tmpl' },
};

my $cgi = CGI->new();
my $action = $cgi->param('action');

if ( defined $action and exists %Actions{$action} ) {
  $Actions{$action}->{code}->($cgi, $action);
}
else {
  $Actions{"default"}->{code}->($cgi, "default");
} #else
# --------------------------------
sub Action1 {
  my ($cgi, $action) = @_;
  my $template = $Actions{$action}->{template};
  ...
} # Action1
# -------------------------