Set references

This section deals with the special statements that assign pointers (references) on existing data objects to field symbols and data references.

When you work with field symbols and data references that contain references to data objects, please note the following:

• At a normal assignment between field symbols, as occurs with the statement MOVE, each field symbol is treated as a dereferenced pointer (value semantics).

• At a normal assignment between data references, as occurs with the statement MOVE, the references are copied (reference semantics). The corresponding rules can be found at the conversion rules for reference variables.

The statements to assign data objects to field symbols and data references are:

• ASSIGN

• UNASSIGN

• GET REFERENCE

Note

If you set references with ASSIGN and GET REFERENCE, then only at the location of the application is a check performed, whether you are allowed to access the corresponding data object or not. After that, the references can be passed on to any destination and you can access the corresponding data objects from any position via the references. To prevent access to private and write-protected attributes via references outside classes, you should not give references to such attributes to the outside.

Note

When setting references with ASSIGN and GET REFERENCE, the check whether the respective data object may be accessed is carried out only at the statement position. After that, the references can be passed on in any way and they can be used at any position to access the assigned data objects. To avoid that references are used to access (write-)protected and private attributes outside of classes, no references to such attributes should be given to the outside.