Preprocessor Procedures

A preprocessor procedure is delimited by %PROCEDURE and %END statements. If the procedure is not defined with a RETURNS attribute, then it may not contain ANSWER statements, but it must not contain any RETURN statements. Conversely, if the procedure is a function, then it must contain at least one RETURN statement, and it must not contain any ANSWER statements.

The statements and groups that can be used within a preprocessor procedure are:

The preprocessor ANSWER statement
The preprocessor assignment statement
The preprocessor CALL statement
The preprocessor DECLARE statement
The preprocessor DO-group
The preprocessor GO TO statement. A GO TO statement appearing in a preprocessor procedure cannot transfer control to a point outside of that procedure.
The preprocessor IF statement
The preprocessor ITERATE statement
The preprocessor LEAVE statement
The preprocessor null statement
The preprocessor NOTE statement
The preprocessor RETURN statement
The preprocessor SELECT-group

Preprocessor statements in a preprocessor procedure do not begin with a percent symbol.

Preprocessor procedures cannot be nested. A preprocessor ENTRY declaration is not permitted in a preprocessor procedure.

A preprocessor procedure entry name, together with the arguments to the procedure, is called a function reference. A preprocessor procedure can be invoked by a function reference in a preprocessor expression, or, if the function procedure name is active, by encountering a function reference in the preprocessor scan of input text. Preprocessor procedure entry names need not be specified in %DECLARE statements.

Provided its entry name is active, a preprocessor procedure need not be scanned before it is invoked. It must, however, be present either in:

The preprocessor input
A string included prior to the point of invocation

The value returned by a preprocessor function (that is, the value of the preprocessor expression in the RETURN statement) replaces the function reference and its associated argument list in the preprocessor output.