How to Write Extensions

Updated 225 Days AgoPublic

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This document will try to walk you through writing, maintaining, and distribute extensions.
For instructions on obtaining and installing extension, see How to Install Extensions
For instructions on using the framework's feature, see another guide that isn't actually written yet.

What are Extensions, really?

capabilities

Kinds of Extensions

• arc
• phorge application
• phorge not-app

Creating an Extension

Requirements

For now, the best way to distribute extensions is by hosting it in a public Git repository. Users will use git clone to install it.

So, you'll need:

• A publicly-available Git hosting - it's available here (on request), and in many other places, such as GitHub.
• A Phorge Development Environment - that is, a computer with PHP, Arcanist, and Phorge installed. Preferably, not one that is used by anyone else. You'll need to configure it for development
• Some familiarity with writing code and using CLI tools.

Anatomy of an Extension

An Extension (sometimes called "a Libphutil library") is mostly made of PHP code, with some of our special glue.

Here's the file structure for a basic application extension:

.
├── LICENSE                      # Optional
├── README.md                    # Also Optional
└── src
    ├── mydemoapp                # All code goes in here!
    │   ├── application
    │   │   └── MyDemoAppApplication.php
    │   └── controller
    │       └── MyDemoAppHomeController.php
    ├── __phutil_library_init__.php
    ├── __phutil_library_map__.php
    └── .phutil_module_cache      # <-- Make sure to add this file to .gitignore!

LICENSE and README.md are optional but recommended.
All your code will go under src/mydemoapp/; There's no requirements beyond that level, but we recommend dividing the files based on their role.
Here we have an Application class and a single Controller class. Note that their names include the extension name; Phorge class-loader doesn't support any sort of Namespace, so each class needs to have its extension name.

__phutil_library_init__.php is the file that makes this a "Libphutil library"; It contains a single instruction, register_library(), with the name of the library. This name has to be unique.
__phutil_library_map__.php is part of the class-loader capability; It includes a list of all classes in the extension.
Both these files are created and updated by running arc liberate. You'll need to re-run this every time you create a new PHP file or change the class hierarchy.

Getting started

To start writing your new extension:

1. git init a new directory for it. (Technically, you don't have to do this, but you really should)
2. cd into this directory, and create the src dir: mkdir -p src
3. Add /src/.phutil_module_cache to the .gitignore file.
4. run arc liberate ./src/ to create an empty library. Arc will prompt you for a name - this has to be a unique name. Keep it lowercase and one word.
5. Assuming you're building a Phorge extension, add the path for your extension in Phorge's conf/local/local.json under "load-libraries":

"load-libraries": [
  "/path/to/my-extension/src"
]

6. Load your Phorge install. You can navigate to /config/ to see installed libraries under "Version Information".
7. Start adding PHP files. Run arc liberate after making changes, and browse to it in Phorge.

There's no "manifest" file for an extension - just the two __phutil*.php files that are loaded.

Writing Code

TODO: add details about how to write an Application and how to write an Arc extension. either here on separate page.

For now: https://we.phorge.it/book/contrib/article/phorge_code_layout/

Publishing Your Extension

When you're ready to publish your extension:

1. Make sure to run arc liberate and celerity map again, and to commit all your files.
2. git push to your selected hosting location.
3. Tell all your friends about it; Provide them with the public clone URI, and this link: How to Install Extensions.
4. Add it to this page: Community Resources

linting and other fun stuff

TODO : write this section

you'll need to add .arclint and .arcunit, but also add the path of phorge/src to load in .arcconfig.

Resources: CSS, JavaScript and Images

TODO: Write this section. This is more how-to-write-the-guide than actual guide.

A Phorge extension can add new CSS and JS files; The basic guide here describing the process for adding and using JS.

Here's an example extension that has CSS and JS files:

.
├──
├── rsrc
│   ├── css
│   │   └── comic-sans.css
│   └── js
│       └── behavior-my-tricks.js
└── src
    ├── mydemoapp
    │   └── celerity
    │       ├── MyDemoAppCelerityResources.php
    │       └── map.php               # This file is generated by `celerity map`
    ├── __phutil_library_init__.php
    └── __phutil_library_map__.php

MyDemoAppCelerityResources.php will look something like this:

final class MyDemoAppCelerityResources extends CelerityResourcesOnDisk {
  public function getName() {
    return 'mydemoapp-resources';
  }

  public function getPathToResources() {
    return phutil_get_library_root('mydemoapp').'/../rsrc';
  }
  public function getPathToMap() {
    return phutil_get_library_root('mydemoapp').'/celerity/map.php';
  }
}

(mydemoapp is the name of the extension library, as defined in __phutil_library_init__.php).

For updating the Celerity map in an extension:

1. Load the extension in Phorge (add it to conf.local)
2. Run ./bin/celerity map from the Phorge directory.

This will update your celerity map in your directory.

TODO: There's also tricks for regular images, and for sprite maps, but I'm not sure what they are.