In A Row

I wrote this a while ago, while reading Behind Deep Blue (which is a great book). It's a chess engine written in ruby. The actual engine is implemented as a move generator, positional evaluator and a board class which handles the state as a set of bitboards and undoable move events.

Included are a command-line client and an xboard interface. The command-line interface accepts coordinate notation and a few commands:

e2e4 - coordinate notation, move a pawn
!play - tell the engine to play as the current color
!undo - roll back a move
!dump filename - store the current board state
!load filename - load a stored board
!reset - start a new game
!quit - end the game

You can cut the verbosity of the generator engine by editing line 121 of evaluator.rb:

@@ -118,7 +118,7 @@ module RubyKnight
                def time_it label
                        start = Time.now
                        res = yield
-                       puts "TIMING( '#{label}=>#{res}'): #{Time.now - start} seconds"
+                       #puts "TIMING( '#{label}=>#{res}'): #{Time.now - start} seconds"
                        res
                end
        end

The evaluator is very primitive, and only thinks one move ahead. Some sort of breadth-first time thinking mode was next on the to-do list.

You can grab the code via git:

git clone http://darkwing.inarow.net/git/rubyknight.git

So, after giving Allan some feedback about the latest less project, Get More Honey, we chatted a bit and it came out that I'm a PHP guy, with a bit of a leaning towards CakePHP. But, I'll fully admit that I love the ruby language, have played with it quite a bit, but simply never had an opportunity to write a rails app. People pay me to write PHP code. ;)

But, it did inspire me to fire up vim and write something in ruby. (Some day I'll dust off RubyKnight, the chess engine I wrote in ruby after reading Behind Deep Blue) Here it is:

#!/usr/bin/ruby
# Written by Chris Moyer (chris@inarow.net // http://inarow.net/)
# Do with it whatever you want.  That's public domain, right?
 
require 'readline'
require 'rubygems'
require 'twitter'
  
user = ARGV[0]
pass = ARGV[1]
  
if !user or !pass then
        puts 'usage: tweet username password'
        exit
end
 
$0 = "tweet #{user} xxxxxxxx"
twitter = Twitter::Base.new(user, pass)
  
while line = Readline::readline('(tweet)> ') do
        Readline::HISTORY.push(line)
        if line.length > 140 then
                puts "#{line.length - 140} characters too long, try again."
        else        
                begin
                        twitter.post(line)
                        puts "Tweeted!"
                rescue 
                        puts "Failed to tweet! (#{$!})"
                end
        end
end
 
puts "\nBye!"

It solves my problem of reading twitter via gtalk, and not wanting to open twitter.com to post... while hating when I underestimate the length of my message and being trunctaed. I can just let this run in window of my screen session, and tweet away.

So, I'd love to hear from the rubyists out there:

• What aspects of this are not good, idiomatic ruby practice?