From: Robert Klemme <shortcutter@...>
Date: 2007-01-18T02:15:05+09:00
Subject: Re: Passing math method to another method?


** SPOILER **

Don't read on if you first want to experiment yourself.


On 17.01.2007 17:48, Neutek wrote:
> Robert, I was actually reading the summation wiki and they had a few
> code examples in C++/Java.. I thought I'd goof a bit and write
> something out in ruby. Of course, I hit the roadblock when trying to
> pass math operators(or methods rather) to a method...

What is the "summation wiki"?  Are you referring to this page?
http://en.wikipedia.org/wiki/Sum

If yes, here are some more ways:

# plain values
sum = (m..n).inject(0){|s,x| s + x}

# with a function
f = lambda {|i| i * 2}
sum = (m..n).inject(0){|s,x| s + f[x]}

# in a method
def sum(m, n, f)
   (m..n).inject(0){|s,x| s + f[x]}
end

s = sum( 1, 2, lambda {|x| x * 2} )

etc.

Advantage of using lambdas is that they are more flexible than method 
names and can contain arbitrary calculations.

Kind regards

	robert


PS: Please don't top post.