From: matz@... (Yukihiro Matsumoto)
Date: 2001-11-10T03:32:05+09:00
Subject: [ruby-talk:24786] Re: Strange behaviour of Array#[]

Hi,

In message "[ruby-talk:24773] Re: Strange behaviour of Array#[]"
    on 01/11/10, "Lyle Johnson" <ljohnson@resgen.com> writes:

|> I believe it's for consistency with Strings:
|
|This is still pretty squirrelly to me, but hey, it's not my language ;)

For these methods, each index points at the edge between elements.

Suppose we have array = [0, 1, 2, 3],

   -4  -3  -2  -1
    +---+---+---+---+
    | 0 | 1 | 2 | 3 |
    +---+---+---+---+
    0   1   2   3   4

when the index is not pointing existing edge, array[idx, n] returns
nil (in this case, idx < -4 or 4 < idx).

Index 4 points the last edge of the array, so it does return a
subarray, which is an empty array since there's no element after the
last edge.

							matz.