SAP DATA REFERENCES documentation, setup help and example usage

ARTICLE

Reference Types
References are pointers to instances. Pointers to data objects are known as data references . Pointers to instances of classes are known as object references . In ABAP, references occur as the content of reference variables. Reference variables are data objects whose data type is a reference type.
Reference types are always created with the addition REF TO . The content of reference variables can be checked using the predicate expression IS BOUND .
The reference type is the static type of a reference variable. It defines the types of the instances its references can point to. The dynamic type of a reference variable is the type from which an object (to which a reference variable points) was instanced. The static type is always more general than or the same as the dynamic type. A dynamic type can be a data type or a class. A reference type or static type can be a type for a data reference variable or object reference variable . The latter is subdivided into class reference variables and
interface reference variables
.
Special conversion rules apply for assignments between reference variables, depending on the static type. These rules ensure that the dynamic type is never more general than the static type ( up cast , down cast ).
Depending on where the object referenced by a reference variable is located, memory-retaining heap references or non-memory-retaining
stack references are used.

Data References

Object References

Heap references and stack references

Notes

From a technical point of view, a reference in ABAP does not refer directly to an object; instead it refers to what is known as a

header that contains the address of the actual object as well as additional information. See also Memory Management of Deep Data Objects .

As well as the regular references in reference variables, weak references represented by objects from a system class can also be used.

Internally, strings , internal tables , and boxed component s are also addressed using references (however these references do not appear as the content of reference variables).

Documentation extract taken from SAP system, � Copyright SAP AG. All rights reserved