custom-ability

custom-ability

generate the ability which can be added to any class directly. It makes custom ability more easy.

API

just one function:

var customAbility = require('custom-ability')

• customAbility(AbilityClass, coreMethod)

arguments

• AbilityClass (function): make the class become to ability.
• coreMethod (string): the core instance method name to identify this ability.
  • it's the key to avoid duplication injection.

return

• (function): a function which can inject the ability to any class directly.

the custom ability function has two arguments: function(class[, options])

• class: the class to be injected the ability.
• options (object): optional options
  • include (array|string): only these emitter methods will be added to the class
  • exclude (array|string): theses emitter methods would not be added to the class
    • note: the coreMethod could not be excluded. It's always added to the class.
  • methods (object): hooked methods to the class
    • key: the method name to hook.
    • value: the new method function
      • use this.super() to call the original method.
      • this.self is the original this object.
  • classMethods (object): hooked class methods to the class

Usage

suppose we wanna add the RefCount ability to any class directly.

the RefCount ability will add the following members to your class. and you should implement the destroy method which will be called by release/free.

• properties:
  • RefCount (integer): the reference count.
• methods:
  • release()/free(): Decrements reference count for this instance. If it is becoming less than 0, the object would be (self) destroyed.
  • addRef(): Increments the reference count for this instance and returns the new reference count.

customAbility = require 'custom-ability'

class RefCountable
  # define the instance methods here:
  release: ->
      result = --@RefCount
      @destroy() unless result >= 0
      result
  free: @::release
  addRef: ->
    if not isUndefined @RefCount
      ++@RefCount
    else
      @RefCount = 1

  # the class methods if any:
  @someClassMethod: ->


module.exports = customAbility RefCountable, 'addRef'

do not forget to add the "ability" keyword to your package.json which means the ability power with it.

// package.json
"keywords": [
  "ability",
  ...
],

do not forget to add the "ability.js" file on your package root folder too.

now user use this ability like this:

refable = require 'ref-object/ability'

class MyClass
  refable MyClass
  destroy: ->console.log 'destroy'


my = new MyClass

my.addRef()
my.free() # nothing
my.free() # print the 'destroy' here.

More complicated example, you can see the events-ex/src/eventable.coffee.