From: Oliver Dain <odain2@...>
Date: 2003-09-05T08:08:06+09:00
Subject: Difference between .. and ... in boolean ranges

I'm a bit confused by some Ruby behavior I'm seeing with ranges.  As I 
understand it the difference between

0..5

and 

0...5

is that the former includes the number 5 while the 2nd does not.  That 
seems to be the case, but one would expect the same type of behavior 
in boolean context.  For example, I'd think

0.upto(9) do |x|
  if (x==3)..(x==5)
    puts "In the range: #{x}"
  else
    puts "Not in the range: #{x}"
  end
end

Would output:

Not in the range: 0
Not in the range: 1
Not in the range: 2
In the range: 3
In the range: 4
In the range: 5
Not in the range: 6
Not in the range: 7
Not in the range: 8
Not in the range: 9

while using the 3 dot form like this:

0.upto(9) do |x|
  if (x==3)...(x==5)
    puts "In the range: #{x}"
  else
    puts "Not in the range: #{x}"
  end
end

Would output:

Not in the range: 0
Not in the range: 1
Not in the range: 2
In the range: 3
In the range: 4
Not in the range: 5
Not in the range: 6
Not in the range: 7
Not in the range: 8
Not in the range: 9

However, the 3 dot form doesn't work as expected.  It outputs the same 
as the 2 dot form (which works as expected).  What gives?  This seems 
unintuitive to me.  Any thoughts?

Thanks,
Oliver