From: Dave Burt <dave@...>
Date: 2006-05-22T17:41:51+09:00
Subject: Re: Array#[] and Out of Range

Christoffer Sawicki wrote:
> Hello.
> 
>> It makes sense. Your subscripts are ranges of indices, not indices. Ruby
>> gives you the subarray specified by the indices in the range. In both of
>> your examples, you get empty arrays. Were you expecting to get arrays of
>> nils?
> 
> I realize I should have added another example:
> 
> [:x][2..x] => nil
> 
> The return values of the two previous examples are actually what I'd
> expected, but it doesn't seem to with consistent with my latest
> example or the documentation. As I read it, in the case of ranges
> "starting index" refers to Range#first.

Further down in the documentation you're referring to:
a = [ "a", "b", "c", "d", "e" ]
...
a[4..7]                #=> [ "e" ]
a[6..10]               #=> nil
...
a[5]                   #=> nil
a[5, 1]                #=> []
a[5..10]               #=> []

This makes sense because a[5..5] needs to return [] for symmetry with
a[0..0].

Cheers,
Dave