ON TIMER block


ON TIMER seconds
   instruction [...]


The ON TIMER seconds clause defines a set of instructions that must be executed at regular intervals. This interaction block can be used, for example, to check if a message has arrived in a queue, and needs to be processed.

Do not mix ON TIMER and ON IDLE clauses.

If the UNBUFFERED option is used in an input dialog, ON IDLE and ON TIMER will flush and validate the current field content. If the field contains invalid data, an error message is displayed, and the corresponding code block is not executed. Therefore, ON IDLE and ON TIMER are not recommended in input dialogs using the UNBUFFERED option.

As ON TIMER can fire field input validation, it is therefore not recommended in dialogs allowing input.

When implementing multiple dialogs with DIALOG block, do not mix several ON IDLE clauses in different sub-dialog blocks: specify a unique ON TIMER clause at the DIALOG block level.

The parameter of ON TIMER must be an integer literal or variable. If the value is zero, the dialog timeout is disabled.

It is not recommended to use the ON TIMER trigger with a short timeout period, such as 1 or 2 seconds. The purpose of this trigger is to give the control back to the program after a reasonable period of time, such as 10, 20 or 60 seconds.
   CALL check_for_messages()

The timer value is taken into account when the dialog initializes its internal data structures. If you use a program variable instead of an integer constant, a change of the variable has no effect if the change takes place after the dialog has initialized. If you want to change the value of the timeout variable, it must be done before the dialog block.

The PROMPT dialog is automatically terminated after ON IDLE, ON TIMER, ON ACTION, or ON KEY block execution.