DEFER INTERRUPT / QUIT
The DEFER instruction defines the program
behavior when interruption or quit signals are received.
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.