From: Christian Neukirchen <chneukirchen@...>
Date: 2005-07-31T20:00:19+09:00
Subject: Re: Higher Order Functions

"Dave Burt" <dave@burt.id.au> writes:

> The problem here is that f(element) means call the method self.f (which 
> doesn't exist, hence the error), whereas you want to call the "function" 
> represented by the parameter f.
>
> You can do this a couple of ways. Charles suggested you pass f as a Method 
> to every:
>> p Functional.every(method(:times_two), [1,2,3]
>> And in Functional, it would be lst.collect { |element| f.call(element)
>> }
>
> f.call will also work if f is a Proc, so you could also do:
>   Functional.every(proc{|x| x * 2}, [1, 2, 3])
>
> You can pass a symbol, but I wouldn't recommend it - make the caller pass a 
> callable object (a Proc or Method).

IMO, you should pass a block.

Then, you still can call it like that:

  Functional.every [1,2,3], &method(:foo)

> Dave 
-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org