DEFER INTERRUPT / QUIT

Syntax

DEFER { INTERRUPT | QUIT }

Usage

The DEFER instruction controls the behavior of the program when an interruption or quit signal has been received.

DEFER INTERRUPT and DEFER QUIT instructions should only be used in the MAIN block, to be executed at the beginning of the program.

DEFER INTERRUPT indicates that the program must continue when it receives an interrupt signal. By default, the program stops when it receives an interrupt signal.

Once deferred, you cannot reset to the default behavior.

When an interrupt signal is caught by the runtime system and DEFER INTERRUPT is used, the int_flag global variable is set to true by the runtime system.

Interrupt signals are raised on terminal consoles when the user presses a key like CTRL-C, depending on the stty configuration. When a program is displayed through a front-end, no terminal console is used; therefore, users cannot send interrupt signals with the CTRL-C key. To send an interruption request from the front-end, you must define an 'interrupt' action view.

DEFER QUIT indicates that the program must continue when it receives a quit signal. By default, the program stops when it receives a quit signal.

When a quit signal is caught by the runtime system and DEFER QUIT is used, the quit_flag global variable is set to true by the runtime system.