Property Accessors Mixin
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' PropertyAccessorsincludeIntothis @::accessor 'type' : -> switch @doorCount when 4 then 'sedan' # i know this isn't strictly accurate when 2 then 'coupe' : switch type when 'sedan' then @doorCount = 4 when 'coupe' then @doorCount = 2 car = car.doorCount = 2cartype # => 'coupe'
You can define a class-level property by extending with the mixin rather than including it (which extends the prototype).
PropertyAccessorsextendthis @accessor 'vehicleCount': -> @allVehicleslength
You can just pass a single function if you only want to define a getter:
PropertyAccessorsincludeIntothis @::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.
PropertyAccessorsincludeIntothis @::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.
@advisedAccessor 'online' : -> @ensureAllSystemsNominal : -> @ensureUserIsSpy station = station.online = true # ensures user is a spy, then assigns true stationonline # ensures all systems are nominal, then returns true