web_root +
  - index.cgi
  + lib
     - App.pm
     - Account.pm
     - ...
  + templates
     - welcome.tmpl
     - login.tmpl
     - ...

# in index.cgi ##########################
use lib "lib";
use App;

my $c = App->new(
  TMPL_PATH => "templates",
  PARAMS    => { .. }
);

$c->run();
#####################################

# in App.pm ###########################
use base "CGI::Application";
use Account;

sub setup {
  my $self = shift;
  
  $self->start_mode("view");
  $self->mode_param("a");
  $self->run_modes(
    "view"   => "view",
    "edit"   => "edit",
    ..
    "verify" => "Account::verify",
    "login"  => "Account::login",
    "logout" => "Account::logout",
    "create account" => "Account::create",
  );
  
}

sub view {
  my $self = shift;
  
  if ($self->session->param("~logged_in")) {
  
	# View stuff
  }
  else {
  	$self->login;
  }
  
}
#####################################

# in Account.pm ########################
package Account;

sub login {
  my ($self, %args) = @_;
  
  # login stuff
  
  $self->view;
}

sub logout {
  my ($self, %args) = @_;
  
  # logout stuff
  
  $self->view;
}
#####################################