Function Groups 

Function groups are containers for function modules. You cannot execute a function group. When you call an function module, the system loads the whole of its function group into the internal session of the calling program (if it has not already been loaded). For further information, refer to Organization of External Procedure Calls.

The following diagram shows the structure of a function group: The name of a function group can be up to 26 characters long. This is used by the system to create the components of the group (main program and corresponding include programs). When you create a function group or function module in the Function Builder , the main program and include programs are generated automatically.

The main program SAPL<fgrp> contains nothing but the INCLUDE statements for the following include programs:

• L<fgrp>TOP. This contains the FUNCTION-POOL statement (equivalent for a function group of the REPORT or PROGRAM statement) and global data declarations for the entire function group.
• L<fgrp>UXX. This contains further INCLUDE statements for the include programs L<fgrp>U01, L<fgrp>U02, ... These includes contain the actual function modules.
• The include programs L<fgrp>F01, L<fgrp>F02, ... can contain the coding of subroutines that can be called with internal subroutine calls from all function modules of the group.

You cannot declare a COMMON PART in a function group. Function groups have their own table work areas (TABLES). Function groups encapsulate data. In this respect, they are a precursor of ABAP Objects (see From Function Groups to Objects ).

All of the function modules in a function group can access the global data of the group. For this reason, you should place all function modules that use the same data in a single function group. For example, if you have a set of function modules that all use the same internal table, you could place them in a function group containing the table definition in its global data.

Like executable programs (type 1) and module pools (type M), function groups can contain screens, selection screens, and lists. User input is processed either in dialog modules or in the corresponding event blocks in the main program of the function group. There are special include programs in which you can write this code. In this way, you can use function groups to encapsulate single screens or screen sequences.