Structure Enhancements

1. Structure Enhancement Possibilities
2. Problems Caused by Structure Enhancements
3. Enhancement Classification in the Dictionary
4. Enhancement Handling in Program Check

1. Structure Enhancement Possibilities

Customers can enhance structures and tables, defined by SAP in the ABAP Dictionary, in the following ways:

• Customizing Includes
  With this variant, there are already certain points within a structure or table reserved for enhancements. However, the corresponding includes are created by the customer.

• Appends
  With this variant, any specified fields are added to the end of structures or tables, without previous reservation.

These types of enhancements affect not only the enhanced structures and tables themselves, but also all dependent structures that adopt the enhancement as an include or substructure. For example, if an enhancement using an Append takes effect only at the end of the initial structure, it will affect all the dependent structures.

2. Problems Caused by Structure Enhancements

In programs without active Unicode check, structure enhancements can cause significant problems with type checks or if used in connection with deep structures, leading both to syntax and runtime errors. In programs with active Unicode check, assignments, operand checks, and accesses using offset and length are also affected and problems can arise. For example, if a purely character-type structure is enhanced by inserting numeric or deep components, it can lose its character-type nature. Enhancements cause further problems because they can change the Fragment View and hence affect the checks (based on the fragment view) for assignments and comparisons.

3. Enhancement Classification in the Dictionary

So that the effects of structure enhancements are visible, you can classify structures and tables in the Dictionary under Extras → Enhancement Category as follows:

Character-type includes elementary types C, D, N, and T; numeric includes the elementary types F, I, P, and X. The deep types STRING and XSTRING are not supported.

Notes

• For structures and tables with includes or substructures, the enhancement categories of these includes and substructures cannot be lower than those of the initial structure. For example, if the initial structure contains a level 4 include, that initial structure cannot be a more restrictive level 2 or 3 structure.

• Structure enhancements in the Dictionary can also affectinternal structures in ABAP programs if Dictionary structures are used as an include or substructure in the source code. These dependencies are implicitly taken into account in the ABAP program check. This also includes non-classified structures containing includes or substructures that can be enhanced.
  
  
  
  

4. Enhancement Handling in Program Check

The ABAP program check uses the structure enhancement classification in the Dictionary to indicate all points in the source code that can lead to problems in connection with structure enhancements. The warnings are separated into three classes, depending on the effects of the permissible structure enhancements:

Notes

All structure enhancement checks are only effective in programs with an active Unicode check. Only static checks are carried out and no checks at runtime. The check also includes non-classified structures and tables, as long as the initial structure contains includes or substructures that can be enhanced.