tick

A small Lua module that simplifies the calling of functions at a set interval or after a delay.

Usage

The tick.lua file should be dropped into an existing project and required by it.

tick = require "tick"

At the start of each frame tick.update() should be called and given the delta time since the last call as its argument.

tick.update(dt)

tick.delay(fn, delay)

Calls the function fn after the given delay time has passed. Returns the associated event.

-- Prints "Hello world!" after 2 seconds
tick.delay(function() print("Hello world!") end, 2)

tick.recur(fn, delay)

Calls the function fn at an interval of delay. Returns the associated event.

-- Prints "tick!" every half-second
tick.recur(function() print("tick!") end, .5)

Chaining events

To avoid having to deeply nest several functions when creating chains of events, the :after() method can be called on an event returned by tick.delay(). You can keep using the :after() method to create complex timed sequences.

-- Prints "cat", "dog", then "owl", waiting 1 second between each print
tick.delay(function() print("cat") end, 1)
  :after(function() print("dog") end, 1)
  :after(function() print("owl") end, 1)

Stopping events

An event can be stopped and removed at any point by calling its :stop() method. To do this the event must be assigned to a variable when it is created.

-- Create a new event
local t = tick.delay(function() print("tick!") end, 10)
-- Remove the event before it has a chance to run
t:stop()

Groups

Tick provides the ability to create event groups; these are objects which can have events added to them, and which are in charge of updating and handling their contained events. A group is created by calling the tick.group() function.

local group = tick.group()

Once a group is created it acts independently of the tick object, and must be updated each frame using its own update method.

group:update(dt)

To add a events to a group, the group's :delay() or :recur() methods should be used.

group:delay(function() print("hello world") end, 4)

A good example of where groups are useful is for games where you may have a set of events which effect objects in the game world and which you want to pause when the game is paused. A group's events can be paused by simply neglecting to call its update() method; when a group is destroyed its events are also destroyed.

License

This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.