From: Daniel Finnie <dan@...>
Date: 2008-05-04T10:06:01+09:00
Subject: Re: Matrix-element extractor -- How to define it

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
<RichardDummyMailbox58407@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
>
>