References the value of an argument that a
procedure passes to a called external procedure file or to an include
file.
ABL converts each argument to a character format. This
conversion removes the surrounding double-quotes if the parameter
was specified as a character string constant in the RUN statement
or include file reference.
When one procedure is called from
another and arguments are used, ABL recompiles the called procedure,
substituting the arguments that the calling procedure passes, and
then runs the called procedure.
Syntax
{ { n | &argument-name } }
|
Enter the braces ({}) as shown; they do not
represent syntax notation in this description.
-
n
- The number of the argument being referred to. If n =
0, ABL substitutes the name of the current procedure (the name you
used when you called it, not the full pathname) as the argument.
If n = *, ABL substitutes all arguments that
the calling procedure passes (but not the name {0}). If you refer to
the nth parameter and the calling procedure does
not supply it, {n} is ignored.
- &argument-name
- The name of the argument being referred to. If you refer to
an argument-name and the calling procedure does
not supply it, ABL ignores {&argument-name}.
If argument-name is
an asterisk (*), ABL substitutes all arguments that the calling
procedure passes. It also adds quotation marks to each parameter,
so you can pass the named argument list through multiple levels
of include files.
Note: It is invalid to pass
both numbered and named arguments within a single pair of braces.
Although this will not cause a compile-time or run-time error, the
arguments will not be passed correctly.
Examples
The
procedure r-arg.p runs procedure r-arg2.p,
passing the arguments customer and name to r-arg2.p.
ABL substitutes these arguments for {1} and {2} in the r-arg2.p procedure.
r-arg.p
RUN r-arg2.p "customer" "name"
|
r-arg2.p
FOR EACH {1}:
DISPLAY {2}.
END.
|
The r-inc.p procedure defines
the variables txt and num, and
assigns the values "Progress VERSION" and "7" to them. The r-inc.p procedure
includes the r-inc.ifile and passes the &int and &str arguments
to the include file. Because the parameters are named, their order
is unimportant. The called procedure can find each argument, regardless
of placement. The r-inc.i include file displays
a message that consists of the passed arguments. The asterisk argument
displays all the parameters as they are listed in the r-inc.p procedure.
r-inc.p
DEFINE VARIABLE cTxt AS CHARACTER NO-UNDO.
DEFINE VARIABLE iNum AS INTEGER NO-UNDO.
ASSIGN
cTxt = "Progress VERSION"
iNum = 7.
{r-inc.i &int=iNum &str=cTxt}
|
r-inc.i
MESSAGE {&str} /* the &str named argument */
{&int}. /* the &int named argument */
MESSAGE "An asterisk displays all the arguments:"
{*} /* all the arguments passed by the calling procedure */
|
Notes
- If
you pass {} arguments using the RUN statement, you cannot precompile
the called procedure. When ABL compiles a procedure, it must have
all the values the procedure needs. So, if you pass arguments to a
procedure you are calling with the RUN statement, the AVM evaluates those
arguments when the calling procedure is run, not when it is compiled.
- You can use the name of an include file as an argument to another include
file. For example, a reference to {{1}} in an included procedure causes
ABL to include the statements from the file with the name that passed
as the first argument.
- Use DEFINE PARAMETER to define a run-time parameter in a called
subprocedure. Each parameter requires its own DEFINE statement. The
parameters must be specified in the RUN statement in the same order as
defined with DEFINE statements.
- ABL disregards an empty pair of braces ({}).
- The maximum length of the arguments you can pass to an include
file is determined by the Input Characters (-inp) startup
parameter.
- An argument argument-name behaves like a scoped
preprocessor name. Thus, if you define a preprocessor name, argument-name,
its value replaces the value of any argument argument-name passed
to the same file at the point where the preprocessor name, argument-name,
is defined.
