From: Jeremy Bopp <jeremy@...>
Date: 2010-12-01T01:10:41+09:00
Subject: Re: 'require' is not recognised

On 11/30/2010 10:00 AM, Tara Keane wrote:
> thanks for your help - I had forgotten to include benchmark inside 
> quotes so it wasn't picking it up.
> one more quick question...
> 
> require'benchmark'
> iterations = 100000
> a=Benchmark.measure do
>  for i in 1..iterations do
>   x=i
>  end
> end
> 
> In the above code (from Beginning Ruby book)
> what's the difference between benchmark and Benchmark(uppercase)
> Also why 2 periods 1..iterations?

The name benchmark is the name of the file to load which in this case
contains the definition of the Benchmark class/module.  Until you load
the benchmark file, the Benchmark class/module does not exist in your
Ruby session.  Benchmark is uppercase because as a class or module it is
a constant, and Ruby requires that constants' names begin with upper
case letters.

The 1..iterations statement defines a Range object from 1 to the value
of iterations (100000 in this case).  The for statement iterates through
that range, setting i to each value and calling the block each time.
There is a similar statement, 1...iterations (note the 3 dots), that
also defines a Range object.  The .. form creates an inclusive range
while the ... form creates an exclusive range from 1 to iterations - 1:

(1..2).to_a.last   #=> 2
(1...2).to_a.last  #=> 1

-Jeremy