Module: Slickr::Behavior

Defined in:
lib/slickr/behavior.rb

Overview

Behaviors give entities the ability to do things. They should implement the logic to move around the world, detect collision, etc.

A behavior should not care about what entities use it. It should specify all the attribute and methods relevant to what it does.

module Spatiality
  include Slickr::Behavior

  attr_access :x, :y, :speed

  def prepare(options={})
    @x = options.fetch(:x, 0)
    @y = options.fetch(:y, 0)
    @speed = options.fetch(:speed, 0)
  end

  def up(delta)
    self.y -= speed * delta
  end

  def down(delta)
    self.y += speed * delta
  end

  def left(delta)
    self.x -= speed * delta
  end

  def right(delta)
    self.x += speed * delta
  end
end

Preparing

since behaviors are modules that get mixed into entities, we can’t use the normal initialize to set defaults. Instead, Slickr uses a convention of the prepare method.

When you specify an entity should implement some behavior, it’s pushed into the entity’s behavior stack. When that entity is instantiated, it will run through all of its behaviors and prepare each one with the options specified in the entity.

class Hero < Slickr::Entity
  use Spatiality, x: 10, y: 10, speed: 0.2
end

hero = Hero.new
hero.x #=> 10
hero.y #=> 10
hero.speed #=> 0.2

Don’t Clobber Behavior Attributes

Use good OO common-sense here. Don’t create multiple behaviors that all depend on attributes of the same name. Behaviors should be independent of one another.

Instance Method Summary collapse

Instance Method Details

#prepare(*args) ⇒ Object

Raises:



64
65
66
 
# File 'lib/slickr/behavior.rb', line 64

def prepare(*args)
  raise NotImplementedError
end