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=head1 Ask not what your user can do for you...

In many scripts, we need to prompt the end user for information - this
could be a prompt for a file name, a selection from a list of options,
or an answer to a yes/no question.

The traditional approach to this sort of question is to print your
question to STDOUT, read a line from STDIN, and apply some sort of
parsing to the answer...

   use 5.010;
   use strict;
   use warnings;
   
   my $answer;
   until (defined $answer) {
      print "Would you like fries with that?\n";
      $_ = <>;
      $answer = 1 if /^Y/i;
      $answer = 0 if /^N/i;
   }
   
   say "Adding fries!" if $answer;

One issue with this approach is: what happens when your script is not
running in a terminal?

One attempt at solving this problem is L<IO::Prompt::Tiny> and its ilk.
This performs a simple test to determine if the script is running on an
interactive terminal and only prompts the user if the terminal is
interactive. When the script is being run non-interactively (or if the
C<PERL_MM_USE_DEFAULT> environment variable is set), then it returns a
default answer instead.

   use 5.010;
   use strict;
   use warnings;
   use IO::Prompt::Tiny qw(prompt);
   
   my $answer;
   until (defined $answer) {
      # In non-interactive mode, assume they want no fries...
      $_ = prompt("Would you like fries with that?", "No");
      $answer = 1 if /^Y/i;
      $answer = 0 if /^N/i;
   }
   
   say "Adding fries!" if $answer;

The problem with this is that it makes the assumption that when the
terminal is non-interactive, there is absolutely no other way to prompt
the user, and you should be happy with the default answer. This is not
always a good assumption.

=head2 Opening up a dialogue

On some operating systems, double-clicking a Perl file will launch it
without a terminal. In these cases, you can probably interact with the
user by launching a dialog box. But how to do that? Doesn't that
require complex programming in L<Tk> or L<Wx> (modules which are not
in core, and not always straightforward to build)?

Enter L<Ask>. Ask abstracts away the details of interacting with your
user. It will do the terminal interaction test; it will check
C<PERL_MM_USE_DEFAULT>; it will see if the L<Wx>, L<Gtk2> or L<Tk>
modules are installed and usable; it will even use C</usr/bin/zenity>
(a GNOME component for adding GUI dialog boxes to shell scripts) if
it has to.

It will only resort to using the default answer if there's no other
possibility of interacting with the user. Here's our fast food worker
using Ask:

   use 5.010;
   use strict;
   use warnings;
   use Ask qw(question);
   
   my $answer = question("Would you like fries with that?", default => 0);
   say "Adding fries!" if $answer;

=head2 That is the question

In the previous example, we saw a yes-no question. How about something a
bit harder?

   use Ask qw( multiple_choice );
   
   my @answers = multiple_choice(
      "Please choose some pizza toppings...",
      choices => [
         [ sauce        => 'Our famous pizza sauce' ],
         [ cheese       => 'Oozing Mozzarella cheese' ],
         [ ham          => 'Finest Bavarian ham' ],
         [ pepperoni    => 'Spicy pepperoni' ],
         [ onion        => 'Onion slices' ],
         [ tinned_fruit => 'Chunky cuts of fresh pineapple' ],
      ],
   );
   say "Adding $_" for @answers;

Or if you just wish them to choose a single option from a list:

   use Ask qw( single_choice );
   
   my $existance = single_choice(
      "To be, or not to be; that is the question.",
      choices => [
         [ be     => "Be" ],
         [ not_be => "Don't be" ],
      ],