In this post we are going to explore how to use ES7 features to define traits with a brand new module: traits-decorator.
CocktailJS is a small library for NodeJS to help developers defining classes and modules in a better, more readable and organised way. It also explores other technics to reuse code such as Annotations, Traits and Talents.
For those developers who likes Object Oriented Programming, CocktailJS helps to extend your classes without utils, to define modules, and to keep code structure more visually appealing making the code easier to understand and debug.
There is one principle behind CocktailJS’s design: Keep code simple, readable and reusable. Simplicity is key in any design, and writing code is not an exception to that rule.
The entry point in Cocktail is a method named mix(). As in any cocktail, you mix things up. In the mix we can use an existing Object, Module or Class reference and mix it to add more value, like adding more properties or even methods.
Mix Object Example
var cocktail = require('cocktail'),
obj = {
name: 'My Object'
};
cocktail.mix(obj, {
value: 10,
print: function() {
console.log(this.name + ' ' + this.value);
}
});
obj.print(); //MyObject 10
Read more: Quick Start
Annotations are meta-data CocktailJS uses to apply some processes. As meta-data, they are not part of the resulting mix, they are declarative and they bring readability on your code.
A Class Example (Car.js)
var cocktail = require('cocktail');
cocktail.mix({
'@exports': module,
'@as': 'class',
'@properties': {
make: '',
model: '',
year: null
},
constructor: function(make, model, year) {
this.setMake(make);
this.setModel(model);
this.setYear(year);
}
});
Read more: Class Definitions
Traits are Composable Units of Behaviour (You can read more from this paper). Basically, a Trait is a Class, but a special type of Class that has only behaviour (methods) and no state. Traits are an alternative to reuse behaviour in a more predictable manner. They are more robust than Mixins, or Multiple Inheritance since name collisions must be solved by the developer beforehand. If you compose your class with one or more Traits and you have a method defined in more than one place, your program will fail giving no magic rule or any kind of precedence definition.
var cocktail = require('cocktail'),
Login = require('./trait/login');
cocktail.mix({
'@exports': module,
'@as': 'class',
'@traits': [Login]
});
Read More: Starting with Traits
Talents are very similar to Traits, in fact a Trait can be applied as a Talent in CocktailJS. The main difference is that a Talent can be applied to an object or module. So we can define a Talent as a Dynamically Composable Unit of Reuse (you can read more from this paper).
Note: While almost all functionality is implemented, the only missing part from the original paper is the ability to remove a Talent from a given instance.
var cocktail = require('cocktail'),
Login = require('./trait/login'),
user = require('./user');
cocktail.mix(user, {
'@talents': [Login]
});
Read More: Exploring Talents
Use npm to install and save it to your project.
$ npm install cocktail --save
In this post we are going to explore how to use ES7 features to define traits with a brand new module: traits-decorator.
A new version of CocktailJS! CocktailJS v0.7.0 is available on npm! As with all other releases, we try to keep all functionality backward compatible until the very first of 1.0 is released.
A Trait to add AOP advices into Classes/Objects. The methods around, after and before are available on host classes or objects.