Fixes #807
- Document `optional_plugin_dependencies` - Also make `converse-headlines` an optional dependency of `converse-dragresize`
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# Changelog
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## 3.0.1 (Unreleased)
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- #807 Error: Plugin "converse-dragresize" tried to override HeadlinesBoxView but it's not found. [jcbrand]
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## 3.0.0 (2017-03-05)
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- **Breaking changes**:
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@ -1035,6 +1035,7 @@ devices when the intent is to use converse.js as a web app. In this case
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it doesn't make sense to close the control box, as there's often then nothing
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"behind" it that's relevant to the user.
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.. _`strict_plugin_dependencies`:
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strict_plugin_dependencies
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--------------------------
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@ -4,8 +4,8 @@
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.. _`writing-a-plugin`:
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Writing a converse.js plugin
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============================
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Writing a plugin
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================
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.. contents:: Table of Contents
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:depth: 2
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@ -59,15 +59,75 @@ The inner ``_converse`` object is made private in order to safely hide and
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encapsulate sensitive information and methods which should not be exposed
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to any 3rd-party scripts that might be running in the same page.
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An example plugin
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Loading a plugin
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-----------------
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In the example below, you can see how to access 3rd party libraries (such
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Converse.js uses the UMD (Universal Modules Definition) as its module syntax.
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This makes modules loadable via `require.js`, `webpack` or other module
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loaders, but also includable as old-school `<script>` tags in your HTML.
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Here's an example of the plugin shown above wrapped inside a UMD module:
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.. code-block:: javascript
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(function (root, factory) {
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if (typeof define === 'function' && define.amd) {
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// AMD. Register as a module called "myplugin"
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define("myplugin", ["converse"], factory);
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} else {
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// Browser globals. If you're not using a module loader such as require.js,
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// then this line below executes. Make sure that your plugin's <script> tag
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// appears after the one from converse.js.
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factory(converse);
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}
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}(this, function (converse) {
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converse.plugins.add('myplugin', {
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initialize: function () {
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// This method gets called once converse.initialize has been called
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// and the plugin itself has been loaded.
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// Inside this method, you have access to the closured
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// _converse object as an attribute on "this".
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// E.g. this._converse
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},
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});
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});
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Accessing 3rd party libraries
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Immediately inside the module shown above you can access 3rd party libraries (such
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moment, underscore and jQuery) via the ``converse.env`` map.
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There is an ``initialize`` method as you've seen in the example above, and then
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also an ``overrides`` map, which can be used to override functions, objects or
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Backbone views and models of Converse.js.
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The code for it would look something like this:
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.. code-block:: javascript
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// Commonly used utilities and variables can be found under the "env"
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// namespace of the "converse" global.
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var Strophe = converse.env.Strophe,
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$iq = converse.env.$iq,
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$msg = converse.env.$msg,
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$pres = converse.env.$pres,
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$build = converse.env.$build,
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b64_sha1 = converse.env.b64_sha1;
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$ = converse.env.jQuery,
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_ = converse.env._,
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moment = converse.env.moment;
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These dependencies are closured so that they don't pollute the global
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namespace, that's why you need to access them in such a way inside the module.
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Overrides
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---------
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Plugins can override core code or code from other plugins. Refer to the full
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example at the bottom for code details.
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Use the ``overrides`` functionality with caution. It basically resorts to
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monkey patching which pollutes the call stack and can make your code fragile
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@ -78,6 +138,41 @@ A better approach is to listen to the events emitted by Converse.js, and to add
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your code in event handlers. This is however not always possible, in which case
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the overrides are a powerful tool.
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Optional plugin dependencies
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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When using ``overrides``, the code that you want to override (which is either
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in ``converse-core`` or in other plugins), needs to be loaded already by the
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type the ``overrides`` object is being parsed.
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So it's important to include overridden plugins in the AMD ``define`` statement
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at the top of the plugin module.
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However, sometimes you want to override parts of another plugin if it exists, but you
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don't want anything to break if it doesn't exist (for example when using a
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custom build which excludes that plugin). An example is the
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`converse-dragresize <https://github.com/jcbrand/converse.js/blob/master/src/converse-dragresize.js>`_
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plugin, which will add drag-resize handles to the headlines box (which shows
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messages of type ``headline``) but doesn't care if that particular plugin isn't
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actually loaded.
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In this case, you can't specify the plugin as a dependency in the ``define``
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statement at the top of the plugin, since it might not always be available,
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which would cause ``require.js`` to throw an error.
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To resolve this problem we thave the ``optional_dependencies`` Array attribute.
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With this you can specify those dependencies which need to be loaded before
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your plugin, if they exist. If they don't exist, they won't be ignored.
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If the setting :ref:`strict_plugin_dependencies` is set to true,
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an error will be raised if the plugin is not found, thereby making them
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non-optional.
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A full example plugin
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---------------------
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.. code-block:: javascript
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(function (root, factory) {
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@ -128,6 +223,20 @@ the overrides are a powerful tool.
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alert(this._converse.user_settings.initialize_message);
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},
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// Optional dependencies are other plugins which might be
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// overridden or relied upon, and therefore need to be loaded before
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// this plugin. They are called "optional" because they might not be
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// available, in which case any overrides applicable to them will be
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// ignored.
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// It's possible however to make optional dependencies non-optional.
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// If the setting "strict_plugin_dependencies" is set to true,
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// an error will be raised if the plugin is not found.
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//
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// NB: These plugins need to have already been loaded via require.js.
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optional_dependencies: [],
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overrides: {
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// If you want to override some function or a Backbone model or
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// view defined elsewhere in converse.js, then you do that under
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_ = converse.env._;
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converse.plugins.add('converse-dragresize', {
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/* Optional dependencies are other plugins which might be
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* overridden or relied upon, and therefore need to be loaded before
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* this plugin. They are called "optional" because they might not be
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* available, in which case any overrides applicable to them will be
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* ignored.
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*
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* It's possible however to make optional dependencies non-optional.
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* If the setting "strict_plugin_dependencies" is set to true,
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* an error will be raised if the plugin is not found.
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*
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* NB: These plugins need to have already been loaded via require.js.
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*/
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optional_dependencies: ["converse-headline"],
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overrides: {
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// Overrides mentioned here will be picked up by converse.js's
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converse.plugins.add('converse-muc', {
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/* Optional dependencies are other plugins which might be
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* overridden or relied upon, if they exist, otherwise they're ignored.
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* overridden or relied upon, and therefore need to be loaded before
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* this plugin. They are called "optional" because they might not be
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* available, in which case any overrides applicable to them will be
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* ignored.
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*
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* However, if the setting "strict_plugin_dependencies" is set to true,
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* It's possible however to make optional dependencies non-optional.
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* If the setting "strict_plugin_dependencies" is set to true,
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* an error will be raised if the plugin is not found.
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*
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* NB: These plugins need to have already been loaded via require.js.
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