the challange ended and, surprise!, we had two participants and three solutions plus my own one.

Results

• tybalt89 second - 125 points - gold medal - winner!
• tybalt89 first - 119 points - silver medal
• Anonymous Monk - 116 points - bronze medal

Notes about points

Anonymous Monk's solution has a minor defect: it allows also kill snake where snake is not among @animals and also select WHALE take_to desert so is more a relaxed version of what I intended, but I have accept it as valid. The backspace behaviour is implemented only on terms not on the whole line. The logic of the program is very neat and easy to understand: my ethernal gratitude :) 16 XP atm

tybalt89 first attempt is already very nice to see. It runs fine only on Linux (more on this below). The all-in-one-line interface is very appealing, as the use of colors. The backspace beahviour is missing (also more on this below): if you erase cow in select cow and then type doTAB you get back to select cow It has 19 XP atm.

tybalt89 second solution is really, really cute to see (on Linux again: maybe life is too short to support unfriendly OSs? ;): it is what I'd like to see in every interactive commandline utility. It also implements the backspace usage correctly so +10, and despite only 15 XP, because of this it wins the challange.

Notes about implementations

Dear Anonymous Monk maybe you do not want to signup in the monastery because of ... , but it is a pity for us not to be able to answer directly: infact I contacted the author of the Term::Completion module, addressing them to your comments and because of this they published their first github repository for the module. They seems very open to suggestions: feel free to contribute there :) Infact one of my best achivements here was to contribute to convince tybalt89 to abandon Anonymous Monk's cloak and finally signin. Programs proposed by tybalt89 are very smart as always and I will need to study them with a bit of patience before understanding them completely, but you always deserve my gratitude, no fear :)

Both programs by tybalt89 show a rare beahviour on Win32: in effect the backspace works well on terms and on the whole line too, but the output is pested of errors emitted by Term::ReadKey complaining with Use of uninitialized value in subroutine entry at C:/perl5.26.64bit/perl/site/lib/Term/ReadKey.pm line 476.

Line 476 of the file on my pc is Win32PeekChar($File, $_[0]); but is not the same line on cpan, even for the very same 2.38 version. Only calling the program as perl autocompletion-nested-tybalt89.pl 2> nul I get the program running correctly.

I looked at the source of Term::ReadKey but I flew away puzzled very soon.

The nasty error comes out with ReadMode 'cbreak' 'raw' 'ultra-raw' so 3,4,5 and here you have the minimal code to reproduce it:

use strict;
use warnings;

use Term::ReadKey;
$| = 1;

ReadMode 'raw';

while(){
    my $char = ReadKey; 
    # infinite, unbreakable looop without this check
    if ( $char eq 'x' ){
        # broken console on Linux without this!
        ReadMode 'restore';
        last;
    }
    print "[$char]";
}
[download]

What is happening on Win32?

Conclusion

It was very fun for me to see your solutions, as always an answer leads to many other questions.

The prize is a bottle of organic red wine and it can be received here in Roma without any time limit :)

Thanks!

L*