os.pullEvent
 Function os.pullEvent | |
| Waits (yields) until an event occurs | |
| Syntax | os.pullEvent([string filter]) |
| Returns | string event, variable parameters(see table below) |
| Part of | ComputerCraft |
| API | OS |
Examples
 Example | |
| The program requires to wait for a keypress to do something: | |
| Code |
function clear() term.clear() term.setCursorPos (1,1) end while true do clear() print ("Press E to do something.") local event, param1 = os.pullEvent ("char") -- limit os.pullEvent to the char event if param1 == "e" then -- if the returned value was 'e' clear() write ("Name: ") local name = read() print (name) break else clear() print ("Wrong button!") sleep (1.5) -- I don't like a whole 2 seconds but 1 second is too short end end |
| Example | |
| This script shows how the os.pullEvent function can be used as an iterator instead of using a while loop: | |
| Code |
for event, param1 in os.pullEvent do --this will continuously fire an event without the use of a while loop print("Event: "..event) print("Param1: "..param1) end SuicidalSTDz 20:23, 29 March 2013 (MSK) |
Common syntax
event, param1, param2, param3 = os.pullEvent()
Note: This is one of the most commonly used functions that can return multiple values. It works like any other function call (such as "input = read()") except that you can get more than one piece of information back.
How it works
When os.pullEvent() is called, the computer waits until an event occurs. Events can be triggered by several different things, such as a key being pressed or a redstone input changing. They are usually triggered by ComputerCraft itself, when it needs to notify the computer that something happened. They can also be triggered by peripherals, or by your program calling os.queueEvent.
More complicated input, such as "the user typing a line of text," does not correspond to an event. read handles this inside itself by waiting for the user to press a key, then updating the screen, moving the cursor, etc.
Events have a type (which is a string) and 0-5 parameters (which are often but not always strings). No built-in events use more than 3 parameters.
When an event occurs, the event type, followed by the parameters, will be returned. If you have:
event, button, x, y = os.pullEvent()
and the user clicks the mouse at coordinates 5,4 then:
- event will be set to "mouse_click" (the event type)
- button will be set to 0 (the first parameter)
- x will be set to 5 (the second parameter)
- y will be set to 4 (the third parameter)
Note that in this example, we didn't specify a filter. If you specify a filter, then all events of different types will be ignored. If the user inserts a disk, instead of clicking the mouse, then event will be "disk", button will be the side the disk drive is on, and x and y will be nil.
If we wanted to only wait for mouse clicks we could use:
event, button, x, y = os.pullEvent("mouse_click")
which will ignore any events that are not mouse clicks.
If you assign more variables than necessary, the extra ones will be set to nil. If you assign fewer variables than necessary, the extra parameters will be discarded.
Event types
| Name | Description | Parameters | ||
|---|---|---|---|---|
| 1 | 2 | 3 | ||
| char | Fired when text is typed on the keyboard | string the letter typed | ||
| key | Fired when a key is pressed on the keyboard | number numerical keycode | ||
| timer | Fired when a timeout started by os.startTimer() completes | number Value of the timer as returned by os.startTimer() | ||
| alarm | Fired when a time passed to os.setAlarm() is reached | number Value of the alarm as returned by os.setAlarm() | ||
| redstone | Fired when the state of any of the redstone inputs change | |||
| terminate | Fired when a combination of keys CTRL and T is pressed and held for three seconds.
You will not normally see this event, as it is handled inside os.pullEvent. |
|||
| disk | Fired when a disk is inserted into an adjacent disk drive | string side | ||
| disk_eject | Fired when a disk is removed from an adjacent disk drive | string side | ||
| peripheral | Fired when peripheral is attached | string side | ||
| peripheral_detach | Fired when peripheral is removed | string side | ||
| rednet_message | Fired when a rednet message is received from the rednet API | number senderID | string message | number distance travelled |
| http_success | Fired when an attempt to receive text from / post text on a website is successful.
You will not normally see this event as it is handled inside http.get. |
string url of the site | table text on the site | |
| http_failure | Fired when an attempt to receive text from / post text on a website is unsuccessful
You will not normally see this event as it is handled inside http.get. |
string url of the site | ||
| mouse_click | Fired when a mouse button is pressed | number mouse button | number x coordinate | number y coordinate |
| mouse_scroll | Fired when a mousewheel is scrolled. | number scroll direction (-1 for up, 1 for down) | number x coordinate(in screen chars) | number y coordinate(in screen chars) |
| mouse_drag | Fired when the mouse is moved after clicking. | number mouse button | number x coordinate(in screen chars) | number y coordinate(in screen chars) |
| monitor_touch | Fired when a player right click on an advanced monitor connected. | string side | number x coordinate(in screen chars) | number y coordinate(in screen chars) |
| monitor_resize | Fired when a monitor resizes | string side | ||
