ABAP Keyword Documentation → ABAP Programming Guidelines → Robust ABAP → Data Types and Data Objects

Including Structures

Other versions: 7.31 | 7.40 | 7.54

Background

In the program-internal design of structures with the BEGIN OF and END OF additions of the TYPES and DATA statements, you can use the INCLUDE TYPE or INCLUDE STRUCTURE statements to integrate all components of another structure with the current structure at this place without creating a specific substructure. You can specify a name for shared addressing and a suffix to avoid naming conflicts. The ABAP Dictionary provides the same functionality.

Substructures, in contrast, are formed if the components of a structure themselves are structured. A structure with substructures is known as a nested structure.

Rule

Do not include components from structures

Do not integrate the components of other structures by using INCLUDE when declaring a structure. If required, you can include the components in a real substructure.

Details

The reasons for this rule are the following:

The integration of components can lead to naming conflicts. This is particularly problematic if structures of other contexts are integrated and changed retroactively.

Although it is possible to assign a name, the integrated structures cannot be addressed as such without restrictions. The necessary internal type information is individually stored for each integrated component. For the components of a substructure, however, this information is stored only once for the substructure

In contrast to real substructures, structures integrated using INCLUDE cannot be declared as boxed components. A boxed component is a structured component, which is managed through an internal reference and thus supports initial value sharing. This can considerably reduce the memory requirements for rarely filled components.

The statement cancels a chained statement that has been created with BEGIN OF and END OF.

If no real substructures can be formed, you must avoid naming conflicts as far as possible by using suffixes (RENAMING WITH SUFFIX addition). This recommendation also applies to the integration of structures in the ABAP Dictionary, where you cannot always create real substructures (for example, for database tables).

Bad example

The following source code shows the integration of the components of a structure into another structure, which is not recommended according to the above rule.

TYPES:
  BEGIN OF structure_1,
  ...
  END OF structure_1.
TYPES:
  BEGIN OF structure_2,
  ...
  INCLUDE TYPE structure_1 AS sub_structure.
TYPES:
    ...
  END OF structure_2.

Good example

The following source code shows the declaration of a component of a structure as a substructure as recommended in the above rule.

TYPES:
  BEGIN OF structure_1,
   ...
  END OF structure_1.
TYPES:
  BEGIN OF structure_2,
    ...
    sub_structure TYPE structure_1.
    ...
END OF structure_2.