cancel

Type

command

Summary

Removes a message that was queued with the send command and is waiting to be sent.

Syntax

cancel <messageQueueID>

Description

Use the cancel command to get rid of messages that were set up but are no longer required.

The ID number of the message is returned by the send command that sent the message. This number is also the first item of the line corresponding to the message in the pendingMessages function.

All pending messages are automatically canceled when the application quits.

It is common to need to cancel a number of messages when leaving a card or stack, if the messages only pertain to that card or stack. For example, you might have queued a number of messages that create an animated display on the current card, and need to cancel them when the user goes to another card. The best solution in a case like this is to place each messageQueueID in a script local variable, a global variable, or a custom property at the time the message is sent. Then you can cancel all those messages in a repeat loop :

    global gMyPendingMessages # you\'ve stored the message IDs here
    on closeCard
      repeat for each line tThisMessageID in gMyPendingMessages
        cancel tThisMessageID
      end repeat
    end closeCard

Parameters

Name	Type	Description
messageQueueID	integer	The ID number of the message.

Examples

cancel 2298

cancel item 1 of last line of the pendingMessages

# Assume these two handlers in a card script.
# Call scheduleBeep to queue a message
# Call cancelBeep to cancel the pending message

local sMessageID

on scheduleBeep
  send "beep" to this card in 20 seconds
  put the result into sMessageID
end scheduleBeep

on cancelBeep
  cancel sMessageID
end cancelBeep

Related

keyword: item

object: card, stack

command: send

control structure: function, repeat

function: flushEvents, pendingMessages, result

glossary: command, custom property, global, loop, message, script local variable, variable

Compatibility and Support

Introduced

LiveCode 1.0

OS

mac

windows

linux

ios

android

Platforms

desktop

server