From: Albert Schlef <albertschlef@...>
Date: 2008-05-07T17:06:21+09:00
Subject: Re: get method in Array subclass: where's it defined?

RichardOnRails wrote:
> m = Matrix[ [10,20,30], [40,50,60], [70,80,90] ];
> puts m [0] [1].inspect  #  20
> puts m [2] [0].inspect  #  70
> puts m[1].inspect  #  [40, 50, 60]
[...]
> my adaptation of Daniel's suggestion, including sub-
> classing, works with no definition of get anywhere.  And the code runs
> without any visible definition of get

Your code "works with no definition of get anywhere" because it doesn't 
utilize this 'get'. When you do "puts m [0] [1]" you aren't triggering 
your 'get'. That's because "m [0] [1]" is the plain-vanila array 
indexing; it uses one-dimensional indexing. It's exactly like doing "row 
= m[0]; row[1]". Multi-dimentional array indexing means: "m[0,1]". and 
if you tried that you'd trigger the call to 'get', and since it's 
absence, Ruby would complain.

Implementiong your 'get' is no big deal. For a start, replace that 
"get(*args)" with "self[args[0]][args[1]]".
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