QP_action()

Synopsis

     #include <quintus/quintus.h>
     
     int QP_action(action)
     int action;
     

Called to request certain actions of Prolog.

Arguments

action is one of:

QP_ABORT

*Abort to the current break level

QP_REALLY_ABORT

*Abort to top level

QP_STOP

Stop (suspend) process

QP_IGNORE

Do nothing

QP_EXIT

Exit Prolog immediately

QP_MENU

Present action menu

QP_TRACE

Turn on trace mode

QP_DEBUG

Turn on debugging

Description

This function allows the user to make Prolog abort, exit, suspend execution, turn on debugging, or prompt for the desired action.

Calls to QP_action() from an interrupt handler must be viewed as requests. They are requests that will definitely be honored, but not always at the time of the call to QP_action(). If Prolog is in a critical region the action might be delayed to when it has exitted the critical region.

Return Value

QP_ERROR

QP_SUCCESS

Errors

For systems that do not have a toplevel, the actions marked with an asterisk (*) will have no effect other than to make QP_action() return QP_ERROR.

Examples

For a full discussion of QP_action() and examples of its use, see ref-iex-iha