From: "Glenn M. Lewis" <noSpam@...>
Date: 2006-10-12T12:40:11+09:00
Subject: Re: Rubychess

 > No apology necessary... how many projects out there have major
 > version numbers less than 1?  :)

             Thanks, Hal!  I appreciate it.

 > When you say it crashes, do you mean that literally? Or what?

             No, sorry.  It exits with an error message, like this, for example:
kingix is NIL!!!  color=-1... about to crash
./nchess6.rb:1924:in `[]': no implicit conversion from nil to integer (TypeError)
         from ./nchess6.rb:1924:in `Eval'
         from ./nchess6.rb:1918:in `each'
         from ./nchess6.rb:1918:in `Eval'
         from ./nchess6.rb:1781:in `Eval'
         from ./nchess6.rb:2407:in `ABnegaSearchZWTail'
         from ./nchess6.rb:2383:in `times'
         from ./nchess6.rb:2383:in `ABnegaSearchZWTail'
         from ./nchess6.rb:2457:in `ABnegaSearchZWTail'
          ... 11 levels...
         from board.rb:1028:in `PrepareForNextMoveWhenOpponentThinks'
         from board.rb:812:in `replaystart'
         from board.rb:230:in `build'
         from board.rb:1079

While I could easily prevent that particular �crash� from happening, it is indicative of
an error somewhere in the engine that needs to be fixed, so I�m not just plugging the hole,
if that makes any sense.

 > Is part of this in C?

             No, it is 100% pure Ruby.  It is a line-by-line port of the Pythonchess-0.6, with
only one tiny tweak I made myself because I had always wanted the python version to
draw a red box around where it last moved from to where it last moved to, in case I was
looking away when it moved.  :-)

 > Is Ruby's performance acceptable (up till the time it dies)?

             Well, that is an excellent question.  At work, I�ve got a brand new screaming
Core Duo machine, and the performance is great.  But if you run the python version
side-by-side with the Ruby version, the python version is easily 10x faster, and sometimes
100x faster based purely on the �number of nodes� it processes during the game, which
it reports in the GUI.  So most of the time Ruby will process ~200 nodes/second while
python would be processing ~4000 nodes/second.  Sad, but true.  I wish someone
would just step in and make an �-O� flag for ruby that either byte-compiled the script
or native-compiled it and then ran it.  :-)

-- Glenn

 > Hal