HP 3000 Manuals HP 3000 Manuals
ON KEY
The ON KEY statement defines a branch that is to be executed when a
specific branch-during-input key is pressed during execution of an HP
Business BASIC/XL input or READ FORM statement.
Syntax
{CALL subprogram}
ON KEY key_number_list {GOTO line_id }
{GOSUB line_id }
[{;} ]
[{,} LABEL [=] key_label]
[{;} {PRI } ]
[{,} {PRIORITY} [=] priority_level]
Parameters
key_number_list A list of integers selected from the set of [1..8] or
numeric expressions that evaluate to integers in the
range of [1..8] separated by commas or semicolons. This
set indicates which branch-during-input key is to be
trapped. If the integer is not in the specified range,
an error occurs. No more than eight values can be
specified for each statement.
subprogram A valid subprogram name.
line_id A line number or line label.
key_label A quoted string of characters used to fill in the label
field of the user-definable key. The string that you
use is specific for your terminal. If the label is <=
fifteen characters, it is centered in the key label. If
the key label is missing, "f1" through "f8" are used.
priority_level A num_expr between 1 and 15, inclusive, used to
determine the order in which multiple branches specified
by interrupts and branch-during-input statements are
handled. If this option is not selected, the branch is
placed on the interrupt queue with a priority of 1.
Examples
100 ON KEY 1 GOTO 120
110 ON KEY 1 GOTO Help_label
120 ON KEY 3 CALL Help
130 ON KEY 1 CALL Help_routine,LABEL=" HELP "
140 ON KEY 1,2 GOSUB 10,LABEL=Label$
150 ON KEY 4,5 CALL Assist,PRI=4
160 ON KEY 2 CALL Help_entry,LABEL=" HELP ENTRY",PRI=10
170 ON KEY 7,8 CALL Exit_routine,LABEL=" exit",PRIORITY=15
The following example is designed to illustrate the behavior of the ON
KEY statement with regard to labels and priorities.
10 ON KEY 1 CALL Suba; LABEL = "Main"
20 PRESS KEY 1
30 PRINT "Done"
40 SUB Suba
50 ON KEY 1 GOTO Myline;PRIORITY = 4;LABEL = "Suba"
60 PRINT "In Suba"
70 PRESS KEY 1
80 SUBEXIT
90 Myline: PRINT "Myline"
100 SUBEND
Running this program produces the following output:
In Suba
Myline
Done
In line 10, KEY 1 is defined with a call action. Main is the label of
function key 1.
In line 20, KEY 1 is pressed. This causes the Suba routine in lines 40
through 100 to be executed. On line 50 KEY 1 is defined with a GOTO
action. Label "Suba" appears on function key 1. Next, the PRINT
statement in line 60 is executed. Following that, in line 70, KEY 1 is
pressed. Since the priority of KEY 1 is defined to be 4, the action
associated with the ON KEY statement is taken. Remember that KEY 1 was
given a priority of 1 on line 10 and a call action was taken. The call
action remains active unless KEY 1 is redefined with a higher priority in
the subunit. Since this is the case in the above example, line 90 is
executed. Line 100 causes a branch to line 30. The PRINT statement in
line 30 is executed and the program ends.