sack

Sack

Inversion-of-control container for all your dependency injection needs.

Installation

Sack is meant to be used with Browserify, so install with npm:

npm install sack

Rationale

This is a simple Inversion of Control Container. It provides the mechanism you need to have a centralized store of object instances that other types can passive request get injected.

This means that you can have objects use, access, or compose other objects without having to explicitly know how to create / setup / initialize them.

It lets you have a highly-decoupled and framework-independent domain objects.

Usage

The functionality of Sack lies within its Container class.

Registering Objects

Register a dependency with a container with a stringly-typed tag and either a constructor, instance, or closure.

var Container = require('sack').Container;

var container = new Container();

// Create a new instance every request:
container.register('service', MyService);

// Create a new instance on first request, then reuse (singleton-esque):
container.shared('service', MyService);

// Use an existing instance:
container.register('service', new Service());

// Have a (lazily evaluated) callback provide the dependency every request
container.register('service', function() {
  return new MyService();
});

// Use a callback to provide the dependency, but only once (singleton):
container.shared('service', function() {
  return new MyService();
});

Resolving Objects

You can create / request objects via the make() function.

var service = container.make('service');

Expressing Dependencies

Whenever Sack creates an object, it satisfies that object's dependencies by resolving them out of the container as well.

An object expresses its dependency as a constructor parameter, whose name must match a registered object.

function UserEditController(users)
{
  this.users = users;
}

UserEditController.prototype.refreshUsers()
{
  this.users.refresh();
}

Assuming we have registered some implementation for users:

container.register('users', new LocalStorageUsers());

Then making UserEditController via the container will resolve the dependency automatically.

var controller = container.make(UserEditController);

Tern Support

The source files are all decorated with JSDoc3-style annotations that work great with the Tern code inference system. Combined with the Node plugin (see this project's .tern-project file), you can have intelligent autocomplete for methods in this library.

Testing

Testing is done with Tape and can be run with the command npm test.

Automated CI cross-browser testing is provided by Testling.

License

Copyright 2014 Brandon Valosek

Sack is released under the MIT license.

Changelog

1.0.0 (2014-01-19)

• First release