HP TACL - Figure 3-13. Sample Release Handler

Writing an Exception Handler
Developing TACL Routines
107365 Tandem Computers Incorporated 3–21
If the user presses the BREAK key while the processing loop is running, TACL raises
the _BREAK exception and reinvokes the routine. The #CASE function executes the
_BREAK case, displays a message, and exits. If the user enters anything other than
ADD or SUB, the #CASE in the loop raises _ERROR, and TACL reinvokes the routine;
in this situation, the #CASE function takes the _ERROR path, displays a message, and
exits. To invoke this routine, load the associated file and enter:
command_processor
Figure 3-13. Sample Release Handler
?SECTION command_processor ROUTINE
== Exception handler ==
[#CASE [#EXCEPTION]
|_CALL |
== No action required when first called
|_BREAK|
#OUTPUT BREAK key pressed.
#RESET RESULTS FRAMES
#RETURN
|_ERROR|
#OUTPUT Input error occurred.
#RESET RESULTS FRAMES
#RETURN
] == End CASE
== Beginning of body of routine ==
#FRAME
#PUSH cmd
== Filter predefined exceptions only
#FILTER _BREAK _ERROR
== Processing loop: runs until invalid command or BREAK key
[#LOOP |DO|
#SET cmd [#INPUT Enter cmd: ] == Get value from terminal
[#CASE [cmd]
|ADD|
#OUTPUT ADD
|SUB|
#OUTPUT SUB
|OTHERWISE|
#OUTPUT Invalid command
#RAISE _ERROR
] == End CASE
|UNTIL| 0 = 1 == (do forever)
] == End LOOP
#UNFRAME