From: Johannes Ahl-mann <softpro@...>
Date: 2005-02-13T08:55:00+09:00
Subject: Re: difficulty with blocks

hi,

sorry for answering my own post, but i am adopting ruby at an incredible
rate. i know python quite well and it took me literally mere minutes to
get the BASIC hang of blocks... i've been programming in ruby for 3
hours now and it already feels like home! not much cosier than python,
but the block closures and the possibility of continuations drags me
into ruby nonetheless ;-)

well, i've got a rather satisfactory solution to my problem and would now like
to ask whether my implementation can be considered "the ruby way" or if it
feels rather strange to the senior rubiists (i.e. people who have
programmed in ruby for more than 3 hours) *ggg*


### snip ###


def fib_block &block
  a, b = 1, 1
  while true:
    block.call(a)
    a, b = b, a+b
  end
end

require 'generator'
def fibUpTo n, &block
  fibs = Generator.new do |g|
    fib_block {|val| g.yield val}
  end

  while (f = fibs.next()) < n
    block.call(f)
  end
end

def into(anArray)
  return proc {|val| anArray << val}
end
fibUpTo 20, &into(a = [])
puts a


### snip ###

thx and forgive me for answering my own questions. i really shouldn't do
that ;-))

Johannes

P.S.: what is it with the implicit blocks in ruby. i am aware that many
people seem not to be explicitely passing the block into a function, but
i really find that distracting and too much of a perl idiom. is my way
alright, or was it unidiomatic??

P.P.S: is there a better way to write "fib_block {|val| g.yield val}"?
maybe something like "fib_block.apply(g.yield)" or so. i guess not, but
the repetition bothers me!