Nice way to break a reply up into pieces in ruby

Question

Hello, I'm writing an IRCd. For this topic it doesn't really matter if you know much about IRC. Its a simple code style problem.

Quick overview of the problem:

• No message may be longer than 512 characters
• If the message is more, it must be broken into pieces
• The NAMES reply sends all the nicknames of users on a channel, and quickly grows beyond 512 characters.

I currently concocted this marvelous piece of code, it works perfectly. However, its just not "ruby-like". This piece of code is more what you expect in some piece of C code.

# 11 is the number of all fixed characters combined in the reply
pre_length = 11 + servername.length + mynick.length + channel.name.length
list = [""]
i = 0
channel.nicks.each do |nick, client|
  list[i+=1] = "" if list[i].length + nick.length + pre_length > 500
  list[i] << "#{channel.mode_char(client)}#{client.nick} "
end
list.each { |l| send_numeric(RPL_NAMREPLY, channel.name, l.strip) }
send_numeric(RPL_ENDOFNAMES, channel.name)

So my question is, any ideas to do this more nicely?

PS. code has been slightly modified to make it easier to understand out-of-context

Answer 1

To split a string into 512 char strings you can use some Enumerator magic. This requires Ruby 1.8.7 or greater:

long_string.each_char.each_slice(512).map{ |chunk| chunk.join }

Answer 2

I can’t think of a way to simplify the logic, but the Enumerable#inject method captures the pattern of “building up a result while traversing a list”:

stuff = %w(my list of words)
list = stuff.inject([""]) do |result,obj|
  tsst = result[-1] + " " + obj
  if tsst.length > 500 then result << obj else result[-1] = tsst end
  result
end

(Here I’m just working on an array of strings.)