From: Mathieu Bouchard <matju@...>
Date: 2001-03-17T05:02:22+09:00
Subject: [ruby-talk:12752] Undo for Arrays


load "../samples/UndoableArray.rb"

a = UndoableArray[]; p a #=> []
a[3,4] = [42,43,1]; p a  #=> [nil, nil, nil, 42, 43, 1]
a[0,1] = [1,2,3]; p a    #=> [1, 2, 3, nil, nil, 42, 43, 1]
a[2] = nil; p a          #=> [1, 2, nil, nil, nil, 42, 43, 1]
a.compact!; p a          #=> [1, 2, 42, 43, 1]
a.undo; p a              #=> [1, 2, nil, nil, nil, 42, 43, 1]
a.undo; p a              #=> [1, 2, 3, nil, nil, 42, 43, 1]
a.undo; p a              #=> [nil, nil, nil, 42, 43, 1]
a.undo; p a              #=> []



this goes in next version of MetaRuby

matju