Important Notice
The pages on this site contain documentation for very old MS-DOS software,
purely for historical purposes.
If you're looking for up-to-date documentation, particularly for programming,
you should not rely on the information found here, as it will be woefully
out of date.
UEVENT Statement Details
◄Summary► ◄Details► ◄Example► ◄Contents► ◄Index► ◄Back►
──────────────────────────────────────────────────────────────────────────────
UEVENT {ON | OFF | STOP}
Usage Notes
■ The UEVENT statement does not affect form- or control-specific
events. Forms and controls use different event handlers. Use object-
specific events with forms. See: ◄Object Events Summary►
■ If your program contains event-handling statements and you are compiling
from the BC command line, use the /W or /V option. If you do not use
these options and your program contains event traps, Visual Basic
generates the error message, "ON event without /V or /W on command
line." See: ◄BC Command-Line Options►
■ UEVENT ON enables trapping of a user-defined event. A user-defined
event is usually a hardware interrupt (although it can be a software
interrupt). If a user-defined event occurs after a UEVENT ON statement,
the routine specified in the ON UEVENT statement is executed.
■ UEVENT OFF disables trapping of a user-defined event. No trapping takes
place until another UEVENT ON statement is executed. Events occurring
while trapping is off are ignored.
■ UEVENT STOP suspends trapping of a user-defined event. No trapping takes
place until a UEVENT ON statement is executed. Any defined user events
that occur while trapping is suspended are remembered and processed when
the next UEVENT ON statement is executed. However, remembered events are
lost if a UEVENT OFF statement is executed before a UEVENT ON statement
is encountered.
■ When a user-defined trap occurs (that is, the GOSUB is performed), an
automatic UEVENT STOP is executed so that recursive traps cannot take
place. The RETURN from a trapping routine automatically executes a
UEVENT ON statement unless an explicit UEVENT OFF was performed inside
the routine.