core/namespace

Provides an API for creating namespaces for objects, which effectively may be used for creating fields that are not part of objects public API.

  let { ns } = require('sdk/core/namespace');
  let aNamespace = ns();

  aNamespace(publicAPI).secret = secret;

One namespace may be used with multiple objects:

  let { ns } = require('sdk/core/namespace');
  let dom = ns();

  function View(element) {
    let view = Object.create(View.prototype);
    dom(view).element = element;
    // ....
  }
  View.prototype.destroy = function destroy() {
    let { element } = dom(this);
    element.parentNode.removeChild(element);
    // ...
  };
  // ...
  exports.View = View;
  // ...

Also, multiple namespaces can be used with one object:

  // ./widget.js

  let { Cu } = require('chrome');
  let { ns } = require('sdk/core/namespace');
  let { View } = require('./view');

  // Note this is completely independent from View's internal Namespace object.
  let sandboxes = ns();

  function Widget(options) {
    let { element, contentScript } = options;
    let widget = Object.create(Widget.prototype);
    View.call(widget, options.element);
    sandboxes(widget).sandbox = Cu.Sandbox(element.ownerDocument.defaultView);
    // ...
  }
  Widget.prototype = Object.create(View.prototype);
  Widget.prototype.postMessage = function postMessage(message) {
    let { sandbox } = sandboxes(this);
    sandbox.postMessage(JSON.stringify(JSON.parse(message)));
    ...
  };
  Widget.prototype.destroy = function destroy() {
    View.prototype.destroy.call(this);
    // ...
    delete sandboxes(this).sandbox;
  };
  exports.Widget = Widget;

In addition access to the namespace can be shared with other code by just handing them a namespace accessor function.

  let { dom } = require('./view');
  Widget.prototype.setInnerHTML = function setInnerHTML(html) {
    dom(this).element.innerHTML = String(html);
  };