Callbacks

The callback datum /datum/callback represents a proc & the required information to call it. They can be called in a blocking or non-blocking (async) manner.

General Usage

Global proc with no arguments: CALLBACK(GLOBAL_PROC, /proc/do_the_thing)

Global proc with arguments: CALLBACK(GLOBAL_PROC, /proc/do_the_thing, argument1, argument2, argument3)

Proc belonging to an object, defined on that object's type: CALLBACK(some_object, .proc/some_proc) (note that doing it this way instead of an absolute path allows child-types of this type to override the called proc.)

Proc belonging to an object, defined on a parent type: CALLBACK(some_object, /atom/movable/.proc/some_other_proc)

Calling

A callback can be manually called using Invoke().

Example:

var/datum/callback/mycallback = CALLBACK(GLOBAL_PROC, /proc/do_the_thing)
var/return_val = mycallback.Invoke()

Additional arguments may also be passed with invoke, like so:

var/datum/callback/mycallback = CALLBACK(GLOBAL_PROC, /proc/do_the_thing)
var/return_val = mycallback.Invoke(some_argument, some_other_argument)

Invoke() will block until the callback proc returns, and will return that proc's value. If you want to call a proc without waiting for it, use InvokeAsync(), but note that it does not return a value.