(no subject)

[nephariuz]

I need more practice with Ruby mixins, so I thought I'd do a quick port of my Java game/simulation. It looks like the result will be as little as one source file where there used to be dozens of files and folders, a fraction of the number of classes, and a fraction of the line count.

I haven't gotten to mess with mixins much yet, though. What I am learning about is Procs, blocks of code that keep all their context (variables, methods, etc.)

In Java, I always had to call an action object with both the actor and the target, even if the action only cared about one of those two. Now, I just provide a block (I don't even have to create an action object), and refer to the variables I need from the scope in which the block is declared. Magically, even though the block is called from a completely different context, it acts from the block "owner's" perspective.

A code sample is in order...



class Creature
attr_accessor :behaviors, :name
def initialize
@behaviors = []
end
def act(target)
@behaviors.each {|behavior| behavior.perform(target)}
end
end

class Behavior
attr_accessor :actions
def initialize
@actions = []
end
def add_action(&action)
@actions << action
end
def perform(target)
@actions.each {|action| action.call(target)}
end
end

#Add an action to an instance...
cat = Creature.new
cat.name = "Felix"
behavior = Behavior.new
behavior.add_action {|target| puts "#{cat.name} is targeting #{target.name}"}
cat.behaviors << behavior

mouse = Creature.new
mouse.name = "Mickey"
cat.act(mouse)

#Or to a class...
class Dog < Creature
def initialize
super
eat = Behavior.new
eat.add_action {|target| puts "#{self.name} the #{self.class} eats #{target.name}!"}
@behaviors << eat
end
end

dog = Dog.new
dog.name = "Scooby"
dog.act(cat)

Prints:

Felix is targeting Mickey
Scooby the Dog eats Felix!