class-wrapper

{class}

The main goal of this library is to automate some construction routines, that a developer is usually writing by himself, and to provide more flexibility to create new classes. This library suppies:

• ClassBuilder - is the main wrapper that realizes the inheritance, data encapsulation, stores the default values and in result it returns a class. This builder is useful to define custom pre-construction routines by setting the class constructor template.
• Class - is a ClassBuilder with already predefined construction routines. The resulting behavior of how the objects are constructing is similar to the behaviour in C++ - all parent constructors are executing first, starting from the root parent constructor, only then the constructor of the class will be executed. With this there is no need to always explicitly call the parent constructor in each constructor function and pass there all the arguments. The constructor function can contain only the effective code that is needed for a new class.

Defined class properties are treated as default values for a new instance and they are isolated between instances. For example if some class has a simple object in properties (Object, or Array), then each instance will have its own copy of that object.

Requirements

• ES6 classes
• Spread operator (...)
• Function.prototype.bind
• Array.prototype.forEach
• Array.prototype.some

If this library is planned to be used on some environments which are not passing the requirements, then please use v1.x (even transpilers will not help).

Installation

Via NPM (Node Package Manager)

$ npm install class-wrapper --save

Then just import the required component

import {Class} from 'class-wrapper';

Or

const Class = require('class-wrapper/dest/class-wrapper.amd').Class;

Usage examples

import {Class} from 'class-wrapper';


// Define a Figure class:
const Figure = Class(function() {
	console.log(`Figure::constructor(${[...arguments].join()})`);
}, {
	// this will set the name for the class, so by debugging you will see correct name of the class, othervise "Class" will be displayed
	__name: 'Figure',

	// abstract function for a calculating an area of a figure
	calcArea() {}
});

// Define Rectangle class derived from a Figure class:
const Rectangle = Class(Figure, function(width, height) {
	console.log('Rectangle::constructor(${[...arguments].join()})');

	if (width !== undefined) {
		this._width = width;
	}
	if(height !== undefined) {
		this._height = height;
	}
}, {
	__name: 'Rectangle',

	_width: 0,
	_height: 0,

	calcArea() {
		return this._width * this._height;
	}
});

// Define Square class as a special case of Rectangle:
const Square = Class(Rectangle, function(length) {
	console.log('Square::constructor(${[...arguments].join()})');

	this._height = length;
}, {
	__name: 'Square'
});



// Create a rectangle with width 2 and height 4
const someRect = new Rectangle(2, 4);
// console will print:
// --> Figure::constructor(2,4)
// --> Rectangle::constructor(2,4)

console.log(someRect.calcArea());			// --> 8

// Create a rectangle with default width and height
console.log((new Rectangle()).calcArea());	// --> 0


// Create a square with an edge length 5
const someSqrt = new Square(5);
// console will print:
// --> Figure::constructor(5)
// --> Rectangle::constructor(5)
// --> Square::constructor(5)

console.log(someSqrt.calcArea());			// --> 25

Links

• wiki
• API
• Run unit tests