From: RichardOnRails <RichardDummyMailbox58407@...>
Date: 2008-05-05T05:40:02+09:00
Subject: Re: Matrix-element extractor -- How to define it

On May 3, 9:06 pm, Daniel Finnie <d...@danfinnie.com> wrote:
> Hi,
>
> You do this:
> class Array
>   alias old_[] []
>   def [] *args
>     if *args.length == 2 && args[0].is_a? Integer && args[1].is_a? Integer
>       get(*args)
>     else
>       old_[](*args)
>   end
> end
>
> Of course, this would remove some of the functionality of an Array for
> every Array, not just matricies.  Consider making a subclass of Array
> like this:
> class Matrix < Array
>   ...
> end
>
> Now you can modify Matrix at will without affecting Array.
>
> If you are creating a Matrix for purely pragmatic reasons (i.e., not
> as an excercise) then there is an excellent Matrix class in the Ruby
> standard library:http://ruby-doc.org/stdlib/
>
> Dan
>
> On Sat, May 3, 2008 at 4:05 PM, RichardOnRails
>
> <RichardDummyMailbox58...@uscomputergurus.com> wrote:
> > Hi,
>
> >  I defined and populated a 9x9 matrix (Array of Arrays) of strings, m
>
> >  I defined an element-extractor:
>
> >  class Array
> >         def get(i,j)
> >                 line =self[i-1]
> >                 char = line[j-1]
> >         end
> >  end
>
> >  To get the first element of the second row, I used the following,
> >  which worked fine:
>
> >  m.get(2,1)
>
> >  I'd like to write merely m(2,1).  How can I do that simply?
>
> >  Thanks in Advance,
> >  Richard

Hi Daniel,

Thanks for the "kick start" and the Matrix class.  I got the latter
working,  but I'm going to "roll my own" because I want a Sudoku
solver that works the way I do manually.  I know there's a free solver
written in VisualProlog, but like Frank Sinatra, "I'll do it my
way" :-)

>     alias old_[] []

I'm running ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32].  It
barfed on "old_", so I substituted:
    else
      super(*args)
which worked fine.

Best wishes,
Richard