in reply to General pattern for interactive text-mode script?

Here's a simple FSM implementation. Each subroutine returns the next 'state' (just a subroutine name) to pass control to. To exit, return undef. 
my $state = "start";
while (my $next = $state->()) {
  $state = $next;
}

sub start {
  ...get input...
  if (/1/) { return "menu_1" }
  elsif (/2/) { return "menu_2" }
  ...
}

sub menu_1 {
  ...
}

sub menu_2 {
 ...
}

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Re^2: General pattern for interactive text-mode script?
by wazoox (Prior) on Jul 04, 2008 at 10:38 UTC
    Hu, this breaks strictures, better use code references : 
    use strict;
use warnings;

my $state = \&start;
while (my $next = $state->()) {
  $state = $next;
}

sub start {
  ...get input...
  if (/1/) { return \&menu_1 }
  elsif (/2/) { return \&menu_2 }
  ...
}

sub menu_1 {
  ...
}

sub menu_2 {
 ...
}

    [download]
    By the way instead of chaining multiple if () {} blocks, using a dispatch table is more efficient and looks nicer: 
    use strict;
use warnings;

my $state = \&start;
while (my $next = $state->()) {
  $state = $next;
}

sub start {
  my %next_action = ( 1 => \&menu_1,
                           2 => \&menu_2,
                           3 => \&menu_3,
                    );

  return $next_action{$_} if exists $next_action{$_}
}

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