From: Johannes Ahl-mann <softpro@...>
Date: 2005-02-13T08:34:59+09:00
Subject: difficulty with blocks

i am still in my early stages of ruby, so please forgive me any
blatantly lacking insight ;-))

i wonder how to divide responsibilities of block-driven methods in ruby.
in python i can divide the responsibilities of creating data and
filtering it using generators and the functional itertools. although
this is a lot of lately tacked on functionality i am struggling to
implement something similar in ruby.

--- python code (untested code, but should run ;-) ---

def fib:
	a, b = 1, 1
	while true:
		yield a
		a, b = b, a+b

import itertools
def fibUpTo(n):
	return itertools.takeWhile(lambda i: i < n, fib())

--- a unified solution in ruby: ---

def fibUpTo n, &block
  a, b = 1, 1
  while a < n
    block.call(a)
    a, b = b, a+b
  end
end

--- snip ---

i would really like to separate the creation of the fibonacci series
from the filtering. this should be possible in ruby, i just can't see it
right now ;-))
is maybe building a generator with the generator module an option?a

thx,
 Johannes