CfgPatches

CfgPatches is a header class of an addon. Placed in Config.cpp, it contains information about requirements, content and meta data describing the addon.

If the config doesn't contain CfgPatches, it is ignored when the game is loading addons on startup.

Configuration

Root

Most commonly, config.cpp file is placed in addon folder's root.

MyAddon\config.cpp

class CfgPatches
{
	class MyAddon
	{
		// Meta information for editor
		name = "My Addon";
		author = "Me";
		url = "http://xkcd.com";

		// Minimum compatible version. When the game's version is lower, pop-up warning will appear when launching the game. (Seems to have no effect in Arma 3 v2.03)
		requiredVersion = 1.60; 
		// Required addons, used for setting load order.
		// When any of the addons is missing, pop-up warning will appear when launching the game.
		requiredAddons[] = { "A3_Functions_F" };
		// List of objects (CfgVehicles classes) contained in the addon. Important also for Zeus content (units and groups) unlocking.
		units[] = {};
		// List of weapons (CfgWeapons classes) contained in the addon.
		weapons[] = {};
	};
};

requiredAddons is the most important setting, because it defines initialization order of addons. If addon B requires addon A, then it will be loaded only once A is loaded as well. This is extremely crucial for making sure Class Inheritance works as intended. If an addon is using some assets from addon C (e.g., textures, sounds, etc.), it is a good practice to make C a required addons.

Sub-folders

Additional config.cpp files can be also placed in sub-folders of an addon (/PBO), they are treated as individual addons by the game.

To make configuration of meta data simpler, you can simply create a link to the root class instead of defining name, author and url again. A good practice is to have all configs withing one PBO to use the same meta data.

MyAddon\Weapons\config.cpp

class CfgPatches
{
	class MyAddon_Weapons
	{
		// Use meta information from specified addon. Used to avoid repeated declarations.
		addonRootClass = "MyAddon";

		requiredVersion = 1.60;
		requiredAddons[] = { "MyAddon" };
		units[] = {};
		weapons[] = {};
	};
};

Scenario Design

When a designer is saving a scenario, meta data of all required addons are saved to mission.sqm as well. When someone else attempts to load the scenario without having the required addons, he will be shown a list of all addons including meta data, even though he doesn't have the addons where they're defined.

Introduced to Eden Editor in 1.60