Skinny Coffee Machine - A Simple State Machine with Observers

ifredwu@gmail.com (Fred Wu) — Thu, 06 Sep 2012 11:47:00 +0000

After a few nights of working on the 2.0 rewrite of jQuery Endless Scroll, I am now releasing one of the tools I built for the project: Skinny Coffee Machine.

Skinny Coffee Machine is a simple JavaScript state machine written in CoffeeScript.

It is fairly simple to use, with the flexibility of adding and removing observers for state transitions.

Define State Machines

@coffeeMachine.power = new SkinnyCoffeeMachine
  default: 'off'
  events:
    turnOn:
      off: 'on'
    turnOff:
      on: 'off'
  on:
    turnOn: (from, to) -> "#{from.toUpperCase()} to #{to.toUpperCase()}"
    turnOff: (from, to) -> "#{from.toUpperCase()} to #{to.toUpperCase()}"
  before:
    turnOff: (from, to) -> "Before switching to #{to.toUpperCase()}"
  after:
    turnOn: (from, to) -> "After switching to #{to.toUpperCase()}"
    turnOff: (from, to) -> "After switching to #{to.toUpperCase()}"

@coffeeMachine.mode = new SkinnyCoffeeMachine
  default: 'latte'
  events:
    next:
      latte: 'cappuccino'
      cappuccino: 'espresso'
      espresso: 'lungo'
      lungo: 'latte'
    last:
      latte: 'lungo'
      lungo: 'espresso'
      espresso: 'cappuccino'
      cappuccino: 'latte'

Switch/Change States

@coffeeMachine.power.currentState() #=> "off"
@coffeeMachine.power.switch('turnOn')
@coffeeMachine.power.currentState() #=> "on"

@coffeeMachine.mode.currentState() #=> "latte"
@coffeeMachine.mode.change('next', 3)
@coffeeMachine.mode.currentState() #=> "cappuccino"

Observers

@coffeeMachine.power.observeBefore('turnOn').start 'labelA', (from, to) => "Observer A before switching to #{to.toUpperCase()}"
@coffeeMachine.power.observeOn( 'turnOn').start 'labelB', (from, to) => "Observer B on switching to #{to.toUpperCase()}"
@coffeeMachine.power.observeAfter( 'turnOn').start 'labelC', (from, to) => "Observer C after switching to #{to.toUpperCase()}"

@coffeeMachine.power.observeBefore('turnOn').stop('labelA')

Go check out the source code now! :)

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Blog (javascript) - Fred Wu's Tech

Skinny Coffee Machine - A Simple State Machine with Observers

Define State Machines

Switch/Change States

Observers