Section 3 Developing Tacl Routines; Processing Arguments; Index - HP TACL Programming Manual

3 Developing TACL Routines

Processing Arguments

TACL routines provide features that you cannot obtain from any other type of TACL
variable. In a routine, you can:
Use #ARGUMENT to check the syntax and validity of several types of arguments
or to parse data within your program
Use #RESULT to return a specific result (instead of an expansion of text)
Use #ROUTINENAME to obtain the name of the active routine, for issuing
recursive calls
Use #RETURN to exit from any location in the routine
Create an exception handler that processes events or errors
The following subsections describe how to use these features.
When you invoke a routine, you can include a list of arguments after the routine name.
A routine does not, however, access these arguments in the same manner as macro
arguments (%n%). Instead, in your routine, you specify an #ARGUMENT function
with a list of argument alternatives. The #ARGUMENT function steps through the list
and checks to see if the current argument matches a specified alternative. If the
argument matches, #ARGUMENT returns an index to the alternative and optionally
stores the argument in a variable for use within the routine.
The following statement checks to see if the next argument is a valid subvolume name
(SUBVOL alternative) or system name (SYSTEMNAME alternative):
#SET num [#ARGUMENT /VALUE name/ SUBVOL SYSTEMNAME]
If the argument is a valid subvolume name, #ARGUMENT assigns 1 to num, indicating
that the argument is a subvolume name, and stores the qualified argument in name.
(The VALUE option affects how the #ARGUMENT built-in function stores the
argument. For more information, see the TACL Reference Manual.)
The following examples show differences between argument processing in macros and
routines. The programs support the following syntax:
process_argm file-name
process_argr file-name
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