docs » hs.timer.delayed

Specialized timer objects to coalesce processing of unpredictable asynchronous events into a single callback

API Overview

API Documentation

Constructors

new
Signature hs.timer.delayed.new(delay, fn) -> hs.timer.delayed object
Type Constructor
Description

Creates a new delayed timer.

Delayed timers have specialized methods that behave differently from regular timers.
When the :start() method is invoked, the timer will wait for delay seconds before calling fn();
this is referred to as the callback countdown. If :start() is invoked again before delay has elapsed,
the countdown starts over again.

You can use a delayed timer to coalesce processing of unpredictable asynchronous events into a single
callback; for example, if you have an event stream that happens in "bursts" of dozens of events at once,
set an appropriate delay to wait for things to settle down, and then your callback will run just once.

Parameters:

  • delay - number of seconds to wait for after a :start() invocation (the "callback countdown")
  • fn - a function to call after delay has fully elapsed without any further :start() invocations

Returns:

  • a new hs.timer.delayed object

Notes:

  • these timers are meant to be long-lived: once instantiated, there's no way to remove them from the run loop; create them once at the module level.

Methods

nextTrigger
Signature hs.timer.delayed:nextTrigger() -> number or nil
Type Method
Description

Returns the time left in the callback countdown

Parameters:

  • None

Returns:

  • if the callback countdown is running, returns the number of seconds until it triggers; otherwise returns nil
running
Signature hs.timer.delayed:running() -> boolean
Type Method
Description

Returns a boolean indicating whether the callback countdown is running

Parameters:

  • None

Returns:

  • a boolean
setDelay
Signature hs.timer.delayed:setDelay(delay) -> hs.timer.delayed object
Type Method
Description

Changes the callback countdown duration

Parameters:

  • None

Returns:

  • the delayed timer object

Notes:

  • if the callback countdown is running, calling this method will restart it
start
Signature hs.timer.delayed:start([delay]) -> hs.timer.delayed object
Type Method
Description

Starts or restarts the callback countdown

Parameters:

  • delay - (optional) if provided, sets the countdown duration to this number of seconds for this time only; subsequent calls to :start() will revert to the original delay (or to the delay set with :setDelay(delay))

Returns:

  • the delayed timer object
stop
Signature hs.timer.delayed:stop() -> hs.timer.delayed object
Type Method
Description

Cancels the callback countdown, if running; the callback will therefore not be triggered

Parameters:

  • None

Returns:

  • the delayed timer object