From: "Shot (Piotr Szotkowski)" <shot@...>
Date: 2008-12-29T06:27:00+09:00
Subject: Re: New to Ruby: copying arrays?

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John Park:

> Stefano Crocco wrote:

>> You can use Marshal.dump and Marshal.load:

>> a =3D [["a", "b"],["c", "d"]]
>> b =3D Marshal.load(Marshal.dump(a))
>> a[0][0].upcase!
>> puts a[0][0]  #=3D> A
>> puts b[0][0]  #=3D> a

> Just experimented with it in irb.
> Awesome! Exactly what I was hoping for!

To extend on the above, what I would do would be to create a separate
Board class to represent your Sudoku board, rather than directly using
Array for this.

First, you can then implement it in various ways, and (as long as you
maintain the same methods to access and opearte on it) it would be
transparent to the Sudoku solver whether your Board is implemented
as an Array of three three-element Arrays, a nine-element =E2=80=98flat=E2=
=80=99
Array, or anything else (say, maybe 27 Sets containing 81 elements
in non-disjoint groups of nines?).

Second, you can then have

class Board
  def dup
    Marshal.load Marshal.dump(self)
  end
end

(which is an idiom I use extensively in my code) and simply use

@initialboard =3D @board.dup
=E2=80=A6
@board =3D @initialboard.dup

in your solver. :)

-- Shot
--=20
FORTRAN was the language of choice for the same reason
that three-legged races are popular.   -- Ken Thompson

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