Timeout: Sometimes Emacs needs one

timeout is a small library to help you throttle or debounce elisp function calls. See this write-up for an introduction and potential uses.

It’s actually tiny, just a couple of functions.

To use this library:

You can throttle an elisp function func to run at most once every 2 seconds:

(timeout-throttle! 'func 2.0)

To reset func:

(timeout-throttle! 'func 0.0)

When the call is a noop, a throttled function will return the same result as the last successful run.

You can debounce an elisp function func to run after an uninterrupted delay of 0.5 seconds:

(timeout-debounce! 'func 0.5)

To reset func:

(timeout-debounce! 'func 0.0)

By default a debounced function returns nil at call time. To change this, run:

(timeout-debounce! 'func 0.5 'some-return-value)

Instead of advising func, you can also create new throttled or debounced versions of it with timeout-throttle and timeout-debounce:

(timeout-throttle 'func 2.0)
(timeout-debounce 'func 0.5)

These return anonymous functions which you can bind to a symbol with defalias or fset:

(defalias 'throttled-func (timeout-throttle 'func 2.0))
(fset     'throttled-func (timeout-throttle 'func 2.0))