From ef5737879e7d311fe1a2148dbe029a583186d291 Mon Sep 17 00:00:00 2001 From: DarkSun Date: Thu, 30 Jul 2020 05:01:33 +0800 Subject: [PATCH] =?UTF-8?q?=E9=80=89=E9=A2=98[tech]:=2020200729=20Demonstr?= =?UTF-8?q?ating=20Perl=20with=20Tic-Tac-Toe,=20Part=204?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit sources/tech/20200729 Demonstrating Perl with Tic-Tac-Toe, Part 4.md --- ...nstrating Perl with Tic-Tac-Toe, Part 4.md | 144 ++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 sources/tech/20200729 Demonstrating Perl with Tic-Tac-Toe, Part 4.md diff --git a/sources/tech/20200729 Demonstrating Perl with Tic-Tac-Toe, Part 4.md b/sources/tech/20200729 Demonstrating Perl with Tic-Tac-Toe, Part 4.md new file mode 100644 index 0000000000..4c7ca4782b --- /dev/null +++ b/sources/tech/20200729 Demonstrating Perl with Tic-Tac-Toe, Part 4.md @@ -0,0 +1,144 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Demonstrating Perl with Tic-Tac-Toe, Part 4) +[#]: via: (https://fedoramagazine.org/demonstrating-perl-with-tic-tac-toe-part-4/) +[#]: author: (Gregory Bartholomew https://fedoramagazine.org/author/glb/) + +Demonstrating Perl with Tic-Tac-Toe, Part 4 +====== + +![][1] + +This is the final article to the series demonstrating Perl with Tic-Tac-Toe. This article provides a module that can compute better game moves than the previously presented modules. For fun, the modules _chip1.pm_ through _chip3.pm_ can be incrementally moved out of the _hal_ subdirectory in reverse order. With each chip that is removed, the game will become easier to play. The game must be restarted each time a chip is removed. + +### An example Perl program + +Copy and paste the below code into a plain text file and use the same one-liner that was provided in the [the first article][2] of this series to strip the leading numbers. Name the version without the line numbers _chip3.pm_ and move it into the _hal_ subdirectory. Use the version of the game that was provided in [the second article][3] so that the below chip will automatically load when placed in the _hal_ subdirectory. Be sure to also include both _chip1.pm_ and _chip2.pm_ from the second [and third][4] articles, respectively, in the _hal_ subdirectory. + +``` +00 # artificial intelligence chip +01 +02 package chip3; +03 require chip2; +04 require chip1; +05 +06 use strict; +07 use warnings; +08 +09 sub moverama { +10 my $game = shift; +11 my @nums = $game =~ /[1-9]/g; +12 my $rama = qr/[1973]/; +13 my %best; +14 +15 for (@nums) { +16 my $ra = $_; +17 next unless $ra =~ $rama; +18 $best{$ra} = 0; +19 for (@nums) { +20 my $ma = $_; +21 next unless $ma =~ $rama; +22 if (($ra-$ma)*(10-$ra-$ma)) { +23 $best{$ra} += 1; +24 } +25 } +26 } +27 +28 @nums = sort { $best{$b} <=> $best{$a} } keys %best; +29 +30 return $nums[0]; +31 } +32 +33 sub hal_move { +34 my $game = shift; +35 my $mark = shift; +36 my @mark = @{ shift; }; +37 my $move; +38 +39 $move = chip2::win_move $game, $mark, \@mark; +40 +41 if (not defined $move) { +42 $mark = ($mark eq $mark[0]) ? $mark[1] : $mark[0]; +43 $move = chip2::win_move $game, $mark, \@mark; +44 } +45 +46 if (not defined $move) { +47 $move = moverama $game; +48 } +49 +50 if (not defined $move) { +51 $move = chip1::hal_move $game; +52 } +53 +54 return $move; +55 } +56 +57 sub complain { +58 print 'Just what do you think you\'re doing, ', +59 ((getpwnam($ENV{'USER'}))[6]||$ENV{'USER'}) =~ s! .*!!r, "?\n"; +60 } +61 +62 sub import { +63 no strict; +64 no warnings; +65 +66 my $p = __PACKAGE__; +67 my $c = caller; +68 +69 *{ $c . '::hal_move' } = \&{ $p . '::hal_move' }; +70 *{ $c . '::complain' } = \&{ $p . '::complain' }; +71 +72 if (&::MARKS->[0] ne &::HAL9K) { +73 @{ &::MARKS } = reverse @{ &::MARKS }; +74 } +75 } +76 +77 1; +``` + +### How it works + +Rather than making a random move or making a move based on probability, this final module to the Perl Tic-Tac-Toe game uses a more [deterministic][5] algorithm to calculate the best move. + +The big takeaway from this Perl module is that it is yet another example of how references can be misused or abused, and as a consequence lead to unexpected program behavior. With the addition of this chip, the computer learns to cheat. Can you figure out how it is cheating? Hints: + + 1. Constants [are implemented as subroutines][6]. + 2. References allow data to be modified out of scope. + + + +### Final notes + +Line 12 demonstrates that a regular expression can be [pre-compiled][7] and stored in a scalar for later use. This is useful as performance optimization when you intend to re-use the same regular expression many times over. + +Line 59 demonstrates that [some system library calls][8] are available directly in Perl’s built-in core functionality. Using the built-in functions alleviates some overhead that would otherwise be required to launch an external program and setup the I/O channels to communicate with it. + +Lines 72 and 73 demonstrate the use of **&::** as [a shorthand for **&main::**][9]. + +The full source code for this Perl game can be cloned from the git repository available here: + +-------------------------------------------------------------------------------- + +via: https://fedoramagazine.org/demonstrating-perl-with-tic-tac-toe-part-4/ + +作者：[Gregory Bartholomew][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://fedoramagazine.org/author/glb/ +[b]: https://github.com/lujun9972 +[1]: https://fedoramagazine.org/wp-content/uploads/2020/02/perl-tic-tac-toe-816x346.png +[2]: https://fedoramagazine.org/demonstrating-perl-with-tic-tac-toe-part-1/ +[3]: https://fedoramagazine.org/demonstrating-perl-with-tic-tac-toe-part-2/ +[4]: https://fedoramagazine.org/demonstrating-perl-with-tic-tac-toe-part-3/ +[5]: https://en.wikipedia.org/wiki/Deterministic_system +[6]: https://perldoc.perl.org/5.32.0/constant.html#TECHNICAL-NOTES +[7]: https://perldoc.perl.org/5.8.2/perlretut.html#Compiling-and-saving-regular-expressions +[8]: https://perldoc.perl.org/5.8.2/functions/getpwnam.html +[9]: https://perldoc.perl.org/perlmod.html#Packages