IS REQUESTED and IS SUPPLIED??

Question

Could anyone let me know what are IS REQUESTED and IS SUPPLIED?

Answer 1

IS REQUESTED
Logical Expressions - Test for Existence of a Formal Parameter
The expression f IS REQUESTED is true if an actual parameter was specified for the formal parameter f when the call was made.
Here, f must be the parameter of a function module, not a pure import parameter (" IMPORTING"). If you are dealing with a structured parameter, it must refer only to the parameter itself, not to a component. Moreover, this is allowed only in the function module itself (not in a subroutine called by the function module).
Example
In a function module, the next test establishes whether the result parameter TEXT was specified when the module was called. The expensive database read operation is executed only if the result is positive.
IF TEXT IS REQUESTED.
  SELECT SINGLE * FROM ...
  TEXT = ...
ENDIF.
Note
Although this test can result in a considerable improvement in performance, it should still be used with caution. In particular, the behavior of a function module (visible from outside) should depend only on the values and not on the existence of actual parameters.
IS SUPPLIED
Logical Expressions - Check for Transfer of an Actual Parameter
Basic form
IF f IS SUPPLIED.
Effect
This variant checks to see whether or not the parameter f was passed at runtime ( IMPORTING) or is to be passed ( EXPORTING) In function modules and methods. The condition is true, if f contains a value, although the system checks only the actual value of the formal parameter, not the default value.
If the parameter is not optional, the system returns a runtime error. If f is a structure, you can only query the parameter itself, not the structure components.
Notes
The logical expression IS SUPPLIED checks only the declaration of an actual parameter when a function module or method is called. If IS SUPPLIED is false for a formal parameter in a procedure, but is nonetheless passed to another procedure as an actual parameter, then IS SUPPLIED is true for the relevant formal parameter in this procedure. Thus, the IS SUPPLIED attribute is not passed on to nested function modules or methods.
You cannot use IS SUPPLIED with update function modules, or asynchronous RFCs.
IS SUPPLIED does not support data exchanges in RFCs unless the function module has the same release status - or higher - as the caller.
Example
A method meth contains the field op as an optional parameter. In the following example, the case condition (using the CASE statement) is true only if op has been passed a value by the calling program.
CLASS test DEFINITION.
  PUBLIC SECTION.
    METHODS meth IMPORTING  op TYPE i OPTIONAL
                 EXCEPTIONS excp.
ENDCLASS.
CLASS test IMPLEMENTATION.
  METHOD meth.
    DATA: feld TYPE i.
    IF op IS SUPPLIED.
      CASE op.
        WHEN 1.
          feld = 100.
        WHEN 2.
          feld = 200.
        WHEN OTHERS.
          RAISE excp.
      ENDCASE.
    ENDIF.
  ENDMETHOD.
ENDCLASS.
Thanks,
Santosh