#
# $Id: future.rb,v 1.5 2003/03/18 13:23:55 fukumoto Exp $
#
# future { ... }
#
# Object
#   future?
#
# Future
#   Future.new { ... }
#   future?
#   __done?
#   __wait__
#   inspect
#   to_a, to_s, ==, =~, ===, method_missing
#   

def future(*param)
  Future.new(param) { |args| yield *args }
end

class Object
  def future?
    false
  end
end

class Future
  def initialize(*param)
    @th = Thread.new(param) { |args|
      begin
	yield(*args)
      rescue
	print $! if $VERBOSE	# ???
	raise
      end
    }
  end

  def future?
    @th.alive?
  end

  def __done?
    not @th.alive?
  end

  def __wait__
    @th.join
  end

  def inspect
    if @th.alive?
      sprintf("#<Future:0x%x>", self.__id__)
    else
      @th.value.inspect
    end
  end

  [:to_a, :to_s, :==, :=~, :===].each do |op|
    eval <<-End
    def #{op}(*args, &block)
      @th.value.__send__(:#{op}, *args, &block)
    end
    End
  end

  def method_missing(name, *args, &p)
    @th.value.__send__ name, *args, &p
  end

end # end of class Future


module Enumerable
  def map_in_parallel
    self.map { |item| future(item) { |i| yield i } }
  end
end


if __FILE__ == $0

  a = (0..9).map { |i| future { sleep 10*rand; i**2 } }

end