Function Modules
Function
modules are procedures that are defined in special ABAP programs only,
so-called function groups, but can be called from all ABAP programs. Function
groups act as containers for function modules that logically belong together.
You create function groups and function modules in the ABAP Workbench using
the
Function
Builder.
Function modules allow you to encapsulate and reuse global functions in the SAP System. They are managed in a central function library. The SAP System contains several predefined functions modules that can be called from any ABAP program. Function modules also play an important role during updating and in interaction between different SAP systems, or between SAP systems and remote systems through remote communications.
Unlike
subroutines, you do not define function modules in the source code of your
program. Instead, you use the
Function Builder.
The actual ABAP interface definition remains hidden from the programmer. You
can define the input parameters of a function module as optional. You can also
assign default values to them. Function modules also support exception
handling. This allows you to catch certain errors while the function module is
running. You can test function modules without having to include them in a
program using the
Function
Builder.
The
Function
Builder also has a release
process for function modules. This ensures that incompatible changes cannot be
made to any function modules that have already been released. This applies
particularly to the interface. Programs that use a released function module
will not cease to work if the function module is changed.