The functions of an ABAP program are implemented in processing blocks. Processing blocks are defined using
modularization statements. You can use
declarative statements in processing blocks of the type
procedure to define local data types and data objects. The other processing blocks do not have a local
data area, and any declarative
statements apply to the program globally. The most important processing blocks in ABAP objects are methods.
You can only implement your class in the implementation part. The order of the processing blocks or
implementation sections is irrelevant for program execution, but should be designed to make the program easy to read.
Following the introductory statement, every program contains a global declaration section, in which you implement the
definitions and declarations that are valid and
visible in the entire program. This includes the declaration of data types and data objects, as well
as the definition of interfaces or the declaration section of classes in ABAP Objects. The definitions
of interfaces and classes contain the declarations of their components. While the order of the individual
definitions and declarations is not specified, you have to take into account that an ABAP statement
can only refer to existing definitions and declarations. For example, a reference variable can only refer to a previously defined class, which in turn can only implement a previously defined interface. Once a
has been introduced, you can declare data types and data objects that are visible within the procedure. The declaration of data types also includes the
typing of objects that have an undetermined data type when the program is created.
All the other statements of an ABAP program are implementation statements, which can always be assigned to a
You use the implementation statements to implement the functions of a processing block. The functions of all processing blocks are largely implemented using the same statements.
Since ABAP is a language that has grown over time, it contains several
obsolete additions to statements that have been replaced
with improved language constructs, but which have not been eliminated in order to ensure downward compatibility.
In ABAP Objects - that is, in the implementation of methods -, almost all of the obsolete language elements
will fail syntax checks. In general, you should no longer use these language elements in new programs, but you may to encounter them in older programs.