From: raja@... (Raja S.)
Date: 2000-12-10T02:40:02+09:00
Subject: [ruby-talk:6975] Re: Accessing an non-existing segment of an array

>> My personal experience has been that when I ask for a segment of an
>> array my intention is: "give me as much as you've got and truncate
>> the rest".  Of course, if that portion itself had nils in it then it
>> is my responsibility to be able to handle them.
>> 
>>      0 1 2 3 4
>> a = [2,3,5,7,11]
>> 
>> b = a[3..10]  #-> [7,11]

>I guess my confusion comes from the intent of the code: why would you
>ever _ask_ for elements outside the bounds of the array?

You are right in that one would generally not -explicitly- ask for elements
outside of the array.  But when you ask for something like a[i..j] one -may-
not always be sure that i & j will be within the current bounds of the
array.  So for primarily, -always- being able to do things along the line of

for x in a[i..j]     or   a[i..j].each {...}
  ...

i was wondering about the return value of a[i..j] for non-existing segments
the merits of [] vs nil.  Python returns [].  Returning nil requires an
explit check before each such iteration.  Which is better?  Though my
preference at the moment is towards [] perhaps i'll need more exposure to
the ruby way to identify the merits of nil.

Regards,
Raja