The following example shows the object-oriented aspect of function groups in the simple case of a counter.
Suppose we have a function group called counter:
DATA count TYPE i.
* Local Interface IMPORTING VALUE(SET_VALUE)
count = set_value.
ADD 1 TO count.
* Local Interface: EXPORTING VALUE(GET_VALUE)
get_value = count.
The function group counter is used as a counter. It has a global integer field count, and three function modules, set_counter, increment_counter, and get_counter, that work with the field. Two of the function modules have input and output parameters. These form the data interface of the function group. From on object-oriented point of view, a function gorup has exclusively private attributes and public methods.
Any ABAP program can then work with this function group. For example:
DATA number TYPE i VALUE 5.
set_value = number.
DO 3 TIMES.
CALL FUNCTION 'INCREMENT_COUNTER'.
get_value = number.
After this section of the program has been processed, the program variable number will have the value 8.
The program itself cannot access the count field in the function group. Operations on this field are fully encapsulated in the function module. The program can only communicate with the function group by calling its function modules.