Assignments between Data Reference Variables

Data reference variables are either completely typed (as of release 6.10) or typed with the generic type data.

Up Cast in Data References

An up cast in data references is possible in the following cases:

• The static types of the source variable and the target variable are identical.

• The static type of the source variable is completely typed (as of release 6.10) and that of the target variable is generic.

Down Cast in Data References

A down cast in data references is only possible if the static type of the source variable is generic and that of the target variable is completely typed. The syntax check precludes that the static types of the source variable and the target variable are both completely typed, but not identical.

Example

Assigning from dref1 to dref2 is an up cast. Assigning from dref2 to dref1 is a down cast, which in this example below leads to an exception. If the statement CREATE DATA had the addition TYPE i, the down cast would also have been successful.

DATA: dref1 TYPE REF TO i,
      dref2 TYPE REF TO data.

CREATE DATA dref1.
dref2 = dref1.
CREATE DATA dref2 TYPE string.

TRY.
  dref1 ?= dref2.
  CATCH cx_sy_move_cast_error.
  ...
ENDTRY.