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    1.1.3 • Public • Published

    Property Accessors Mixin Build Status

    A mixin for defining dynamic properties.

    Basic Usage

    To define a basic property accessor, use the accessor declaration. If you've included the mixin into a class, you define a prototype property by calling @::accessor on its prototype.

    PropertyAccessors = require 'property-accessors'
    class Vehicle
      @::accessor 'type',
        get: ->
          switch @doorCount
            when 4 then 'sedan' # i know this isn't strictly accurate 
            when 2 then 'coupe'
        set: (type) ->
          switch type
            when 'sedan' then @doorCount = 4
            when 'coupe' then @doorCount = 2
    car = new Vehicle
    car.doorCount = 2
    car.type # => 'coupe' 

    You can define a class-level property by extending with the mixin rather than including it (which extends the prototype).

    class Vehicle
      @accessor 'vehicleCount'get: -> @allVehicles.length  

    You can just pass a single function if you only want to define a getter:

    class Vehicle
      @::accessor 'type'-> # ... 

    Fancy Usage

    Lazy Accessors

    Lazy accessors call a function the first time a property is accessed. You are still free to overwrite this value by assigning the property explicitly.

    class ScienceLab
      @::lazyAccessor 'crazyComputation'-> computeCrazyComputation()

    Advised Accessors

    Advised accessors allow you to call code before the reading or writing of a property value. If a property is being assigned, your advice function is called with the value being assigned and the old value.

    class SpyStation
      @advisedAccessor 'online',
        get: -> @ensureAllSystemsNominal()
        set: -> @ensureUserIsSpy()
    station = new SpyStation = true # ensures user is a spy, then assigns true # ensures all systems are nominal, then returns true 


    npm i property-accessors

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