Figure 3-15. Sample Keep Exception Handler - HP TACL Programming Manual

Note The examples in this subsection include an EXIT case for testing purposes, which allows you to exit the
routines. To prohibit exits, delete the EXIT case from the #FILTER statement and from the exception
handler and main loop.
To invoke restricted_cmd_processor, load the file and enter:
restricted_cmd_processor

Figure 3-15. Sample Keep Exception Handler

?SECTION restricted_cmd_processor ROUTINE
[#CASE [#EXCEPTION]
|_CALL |
#FRAME
#PUSH cmd
|_BREAK|
#OUTPUT BREAK key pressed.
|_ERROR|
#OUTPUT TACL error occurred.
|EXIT|
#RESET FRAMES RESULTS
#RETURN
|OTHERWISE|
#OUTPUT Unknown exception occurred.
] == End #CASE
== Filters predefined exceptions only
#FILTER _BREAK _ERROR EXIT
== After you enter this loop, control stays here unless the
== routine is processing an exception.
[#LOOP |DO|
#SET cmd [#INPUT Enter cmd: ]
[#CASE [cmd]
|ADD|
#OUTPUT ADD
|SUB|
#OUTPUT SUB
|EXIT|
#RAISE EXIT
|OTHERWISE|
#OUTPUT Invalid command
#RAISE _ERROR
] == End CASE
|UNTIL| 0
] == End LOOP
#UNFRAME
107365 Tandem Computers Incorporated
== For demo only
Developing TACL Routines
Writing an Exception Handler
== Get value from terminal
== For demo only
== Always false
3–25