From: Philipp Hofmann <phil@...126.de>
Date: 2008-01-26T06:11:10+09:00
Subject: Re: to sleep no more

hi,

ok let's code a zoo. threads is what you are looking for, but there
might be a better way. but threads first.

class Animal

  def initialize
    @lifetime_in_sec = 0
    @dead = false
    thread = Thread.new do
      until @dead
        @lifetime_in_sec += 1
        sleep 1
      end
    end
  end

  def kill
    @dead = true      
  end

end

depending on your zoo this might lead to a lot of threads, so maybe
you should think about using a more event-based design. (make the egg
by initialization register a 'timed' event to become a biddy.)

shutdown = true
$events = Hash.new { |hash, key| hash[key] = [] }
$time = 0

class Animal
  def initialize
    $events[$time+time_to_become_a_biddy] << self
  end
  def progress
    # become a biddy or chicken or ...
    $events[$time+time_to_become_a_chicken] << self if @state==:biddy
  end
end

event_handler = Thread.new do
  counter = 0
  until shutdown
     counter += 1
     $events[counter].each { |animal| animal.progress }
  end
end

this way your simulation is calucaluatet as fast as possible and you
can throttle it to be realtime. asuming your machine is fast enough
for your zoo. ;)

g phil


On Sat, Jan 26, 2008 at 05:19:58AM +0900, DrBenway wrote:
> On Jan 25, 8:27 pm, Stephen Kratzer <kratz...@pa.net> wrote:
> > On Friday 25 January 2008 13:25:00 DrBenway wrote:
> >
> >
> >
> > > hi all,
> >
> > > I'm a ruby noop trying his first steps. I'd like a little advice.
> >
> > > What I want to make is the following.
> >
> > > An object Chicken
> > > - its attribute starts as 'egg'
> > > - after x times sleep() it the attribute gets the value chicken
> > > - x times sleep later the object can make a call to make a new
> > > instance of chicken (creating another egg)
> >
> > > I could make a method to change the attribute and call this from my
> > > main program.
> > > In other words  my sleep method would be in my main program and call
> > > the objects method.
> > > I was wondering if it would be possible to keep the sleep in the
> > > object.
> > > (Since I was planning on creating some other animals as well, each
> > > with a special amount of time needed to go to the next step.)
> >
> > > I think it's called threads in ruby but I'm not sure.  (if it's called
> > > threads is this the way to handle this problem? Does it act like an
> > > Ajax call?)
> >
> > > Many thnx
> >
> > > DrBenway
> >
> > Something like this might work for your purposes:
> >
> > class Animal
> >         attr_reader :incubation_period, :maturation_period, :from_type,
> >                     :to_type, :current_type, :slept, :children
> >
> >         def initialize(i_period = 60, m_period = 120, from = "egg", to
> > = "chicken")
> >                 @incubation_period = i_period
> >                 @maturation_period = m_period
> >                 @slept = 0
> >                 @from_type = from
> >                 @to_type = to
> >                 @current_type = @from_type
> >                 @children = []
> >         end
> >
> >         def mysleep(seconds = @incubation_period)
> >                 @slept += sleep(seconds)
> >                 if @slept >= @incubation_period
> >                         @current_type = @to_type
> >                 end
> >         end
> >
> >         def give_birth(count = 1)
> >                 if @slept >= @maturation_period
> >                         for number in children.length..(children.length +
> > count - 1)
> >                                 puts "I had another child."
> >                                 children[number] =
> > Animal.new(@incubation_period, @maturation_period, @from_type, @to_type);
> >                         end
> >                 else
> >                         puts "I'm too young to give birth."
> >                 end
> >         end
> > end
> >
> > snake = Animal.new(5, 10, "egg", "snake")
> > snake.mysleep(4)
> > puts snake.current_type
> > snake.give_birth
> > snake.mysleep(4)
> > puts snake.current_type
> > snake.give_birth
> > snake.mysleep(4)
> > puts snake.current_type
> > snake.give_birth(5)
> 
> Wow thnx Stephen for coocking up an example so fast :)
> That's indeed what I was planning to do.
> 
> The only thing that may not have been very obvious (sorry for this) in
> my example above was:
> Is there a way to take the snake.mysleep(4) out of our main program
> and put it in the class/object itself
> That way I call  snake = Animal.new(5, 10, "egg", "snake") once and
> from then on it leads a life on its own (that's what got me to think
> that I needed threads).
> Same goes for all the other snakes that get born from the first.
> I don't feel like messing with arrays of
> snakes,pigs,boars,chickens,... out of the classes
> 
>