From: Robert Klemme <bob.news@...>
Date: 2005-08-11T00:31:11+09:00
Subject: Re: Matrix type ?

zimba-tm wrote:
> Hello ruby fellows,
>
> Maybe you can help me.
>
> I'm currently trying to make a Sudoku solver for my first ruby
> program. Sudoku is a nice 9x9 board game with simple rules, but it
> can be tough to solve. More infos at http://www.sudoku.com/ if you
> want to launch a RubyQuizz :-P
>
> What I would do, is use a kind of 2D Matrix that would represent the
> board but couldn't find a satisfying method.
>
> This is my current implementation using arrays :
> ----
> board = Array.new
>
> (1..9).each do |row_num|
>   board[row_num] = Array.new
>   (1..9).each do |col_num|
>     board[row_num][col_num] = "X"
>   end
> end

That can be simplified to

board = Array.new(9) { Array.new(9) { "X" } }

In your case I'd create a customer class that does this internally and
provides access methods to cells.  This class then also can check the
validity of moves etc.

class Board
  def initialize(size=9)
    @board = Array.new(size) { Array.new(size) { "X" } }
  end

  def move(from_x, from_y, to_x, to_y)
    raise "Invalid move" if ...
    # do the move
    ...
  end

  def to_s
    # generate reasonable string representation
    ...
  end
end

You might also need / want classes for figures if they behave differently
etc.

> ----
> If I "puts board", I'd like to have a 2D view instead.
> How does puts work, does it call the to_str method ?

No, it's #to_s:

>> o=Object.new
=> #<Object:0x10180648>
>> puts o
#<Object:0x10180648>
=> nil
>> def o.to_s() "foo" end
=> nil
>> puts o
foo
=> nil

> Also, I'd like to access the console as a 2D Array too,
> so that I can write on screen directly like a text-framebuffer.

Hm, I think there is (n)curses support somewhere.  You can check with the
RAA
http://raa.ruby-lang.org/

> I have so many questions.. :-)
> /me is refraining to flood ruby-talk

Keep coming!

Kind regards

    robert