From: Hal Fulton <hal9000@...>
Date: 2004-07-22T07:19:40+09:00
Subject: Re: substring by range parameter (bug?)

D T wrote:
> OK. You got my point.
> And your explanation seems logic to me.
> Thanks.
> 
> Anyway, I still feel this is very strange...
> "a"[-1..-2] #=> ""
> ""[-1..-2] #=> nil
> 
> My Conclusion is : For any no empty string, it exists exactly string's 
> length + 1 of empty substring!
> (location does matter)
> 
> Example: for "ab", there are exactly 3 empty substrings locate at 
> "^a^b^"  (^ shows empty string position)
> 
> s="ab"; s[-1..-2]="xxx"; p s   #==> s = "axxxb"
> s="ab"; s[-2..-3]="xxx"; p s   #==> s = "xxxab"
> s="ab"; s[1..0]="xxx"; p s     #==> s = "axxxb", it is the same as 
> s[-1..-2]
> s="ab"; s[2..1]="xxx"; p s     #==> s = "abxxx"
> 
> As you can see, there are exactly 3 empty substrings on "ab". (and you 
> can re-assing)  ;-)


This is the most logical analysis of this issue that I remember
seeing. Thank you for that.

And also IMO it's the best justification for this behavior -- after
all, "before the beginning" and "after the end" are valid locations
as far as insertion goes.

I now understand better what matz said long ago, about an imaginary
pointer in between the elements. I understand this better WRT insertion
than WRT accessing data.

Array subranges work much the same way, I believe, correct?


Hal