snowman ☃

Immutable, inheritable objects with information hiding.

The snowman() function creates factory functions for objects with the following features:

• Constant private, protected and public members
• Private, protected and public static members
• "Super" via Object.getPrototypeOf
• Totally immutable objects via Object.freeze

These features allow data to be shared in an exclusive manner, without exposing it for modification or even readability. Implementation details no longer leak, sparing projects from additional maintenance and documentation. Data is more secure, if not completely locked-away, from malicious 3rd-parties. No more object._pinkyPromise.

Let it snow, let it snow, let it snow... ❄

Installing

Browser:

bower install snowman

<script src="bower_components/snowman/snowman.js"></script>

Node:

npm install snowman

Usage

Via browser global:

(function (snowman) {
    var factory = snowman({});
}(window.snowman));

AMD:

require(['snowman'], function (snowman) {
    var factory = snowman({});
});

CommonJS:

var snowman = require('snowman'),
    factory = snowman({});

Examples

(function () {

    'use strict';

    var personFactory = snowman({
        static: {
            protected: {
                isBirthday: function () {
                    var today = new Date();
                    return today.getMonth() === this.birthday.getMonth() &&
                        today.getDate() === this.birthday.getDate();
                }
            },
            public: {
                consultOnAge: function () {
                    console.log('I\'m ' + this.age + '.');
                },
                consultOnBirthday: function () {
                    if (this.isBirthday()) {
                        console.log('It\'s my birthday! How did you guess?');
                    } else {
                        console.log('It\'s my un-birthday.');
                    }
                },
                salutation: function () {
                    console.log('The name\'s ' + this.name + '.');
                }
            }
        },
        local: {
            private: ['birthday'],
            protected: ['age'],
            public: ['name']
        },
        constructor: function (spec) {
            this.birthday = spec.birthday;
            this.age = spec.age;
            this.name = spec.name;
        }
    }),
        potentiallyMoreExperiencedFactory = snowman({
            extends: personFactory,
            static: {
                public: {
                    consultOnAge: function () {
                        var parent = Object.getPrototypeOf(this);
                        if (this.age >= 45) {
                            console.log('None of your business.');
                        } else {
                            parent.consultOnAge();
                        }
                    }
                }
            }
        }),

        joe = personFactory({
            name: 'Joe',
            age: 25,
            birthday: new Date()
        }),

        sam = potentiallyMoreExperiencedFactory({
            name: 'Sam',
            age: 45,
            birthday: new Date(Date.now() - 1000 * 60 * 60 * 24)
        }),

        bobby = potentiallyMoreExperiencedFactory({
            age: 44
        });

    console.log(joe.name); // "Joe"
    console.log(joe.age); // undefined
    console.log(joe.birthday); // undefined
    joe.salutation(); // The name's Joe.
    joe.consultOnBirthday(); // It's my birthday! How did you guess?
    joe.consultOnAge(); // I'm 25.

    console.log(sam.name); // "Sam"
    console.log(sam.age); // undefined
    console.log(sam.birthday); // undefined
    sam.salutation(); // The name's Sam.
    sam.consultOnBirthday(); // It's my un-birthday.
    sam.consultOnAge(); // None of your business.

    bobby.consultOnAge(); // I'm 44.

}());

For more examples, see tests/.

Development

# Watch for changes and run tests.
grunt watch

# Lint, test, build.
grunt