From: walter@...
Date: 2004-03-19T03:37:09+09:00
Subject: Re: Can I stop each's iteration, and get the results so far?

> Basically, I want to break from a find_all, and get the array of
> elements found so far. Is this possible?
> 
> I tried this, no luck with find_all and collect, they return nil,
> instead of the array so far. Any suggestions on how to do this?

This might be overly simplistic, but if this is not going to be used 
by multiple threads simultaneously, and you already know the limit 
ahead of time, why not just set the limit on the object before 
calling the function, and make sure that each limits you to that?


class EveryN
  include Enumerable

  def initialize(n)
    @n = n
  end

  def each
    y = 0
    loop do
      y = y + @n
      break if @max_iteration < y
      yield y 
    end
  end
  
  def max_iteration=(max_iteration)
    @max_iteration = max_iteration
  end
  
end

every = EveryN.new(3)
every.max_iteration = 25
every.each { |n| puts n }

puts "is 20 in every?"

every.max_iteration = 20
p every.detect { |n| n == 20 }

puts "is 21 in every?"

every.max_iteration = 21
p every.detect { |n| n == 21 }

puts "all n between 100 and 200?"

every.max_iteration = 200
p every.find_all { |n| n >= 100}

puts "all n as a string, up to 20"

every.max_iteration = 20
p every.collect { |n| "n is #{n}" }



Walt
*****************************************************
Walter Szewelanczyk
IS Director
M.W. Sewall & CO.        email : walter@mwsewall.com     
259 Front St.            Phone : (207) 442-7994 x 128
Bath, ME 04530           Fax   : (207) 443-6284
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