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From: Jean-Louis Leroy <jll@skynet.be>
Newsgroups: comp.lang.beta
Subject: Beginner at work: two dimensional value-based array generic
Date: Mon, 14 Dec 1998 22:28:11 +0100
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Hello,

As an exercise, I'm attempting to create a generic two-dimensional 
array of values. Here's what I've got so far:

(#
   Array:
     (#
        type:< object;
        nx,ny: @integer;
        data: [0] @type;
        resize:
          (# newx,newy: @integer; singular: @type
          enter (newx,newy)
          do
             (newx*newy)->data.extend;
             (for i: data.range repeat singular->data[i] for);
             (newx,newy)->(nx,ny)
          #);
     #)
#)  


1) singular->data[i] doesn't compile because the compiler sees an 
invalid assignment. I don't see why (it would be nice if the compiler 
reported the types of both sides).

2) I looked at arrayContainer and noticed that the container stores 
references instead of values. OTOH, C++ standard containers are all 
value-based, if you want a container of pointer you simply make a 
container of values that are of pointer type (e.g. vector<Foo*>). When 
my Array pattern works I suppose I can use it as an array of references 
as well:

    arrayOfFooRefs: Array (# type::< ^Foo #)

Will it work? If yes, why is arrayContainer designed the way it is?

Thus far I think that BETA is a fascinating language, I hope I can get 
hold of the books soon and be done asking stupid questions ;)

Jean-Louis Leroy
http://ourworld.compuserve.com/homepages/jl_leroy/