From: Maarten Mortier <maarten.mortier@...>
Date: 2008-12-09T00:07:46+09:00
Subject: filtering blocks

Is it possible to filter blocks, online, in an elegant way?

for instance if I have the block

class Integer
  def divisors
    (1..self).each{ |i| yield i if self % i == 0 }
  end
end

and I want to pass this block through an 'online' filter.

I want to do something elegant like
10.divisors.odd{ |n| puts n }
# instead of
10.divisors{ |n| puts n if n.odd? } #, which is pretty much the same as
10.divisors{ |n| yield n if n.odd? }{|n| puts n}

I suppose it's not possible at all to treat a block as an object in this
manner?

If so, suppose I want to use a generic filter that takes a block and a
condition as its arguments, and returns the block of each elements for
which a condition is fulfilled?

# pseudo
def filter (block, condition)
  block do |s|
    yield s if s.condition
  end
end

How would I do anything like this, without using arrays as inbetweens?
Am I again trying to treat blocks wrongly as objects, is it at all
possible to 'operate' through them in this way?
I'm new to ruby so this might be a bit stupid. I was just experimenting
and couldn't find an elegent, modular manner of filtering blocks
run-time in a 'chain-like' manner, without needlessly compressing them
to arrays in between.

I got this when googling, btw: www.rubyfilter.com :)
-- 
Posted via http://www.ruby-forum.com/.