ABAP Keyword Documentation → ABAP Programming Guidelines → Robust ABAP → Data Types and Data Objects
Reference to Data Types or Data Objects
Other versions: 7.31 | 7.40 | 7.54
Background
As well as using data types
for declarations and typings with the addition TYPE, the alternative addition
LIKE of the corresponding statements can be used to reference the data type
of one of the data objects visible at this position directly. This includes references to data objects
of the same program, interface parameters of the current procedure, attributes of global classes and interfaces, and constants in type groups.
Rule
Declare dependent data objects with reference to other data objects
If a data object directly depends on another data object, refer to it directly using LIKE
for the declaration. In all other cases, use TYPE to refer to a standalone data type.
Details
For example, if a helper variable of the type of an input parameter is required within a procedure
(method), it
should not be declared with reference to the type of the parameter using TYPE
but with reference to the parameter itself using LIKE. It is also possible
to declare work areas using LIKE LINE OF if the parameter is an internal
table. In the case of typing with LIKE, the type of the parameter can be changed retroactively without always having to adapt the procedure implementation.
However, if no close reference to another data object exists, it is usually more useful to declare data objects with reference to a
standalone data type by using TYPE.
Note
Obsolete references to flat structures or database tables or views of the ABAP Dictionary using LIKE should never be implemented.
Bad Example
The following source code shows the declaration of a helper variable in a method that is supposed to
be of the same data type as an interface parameter. The TYPE reference to the data type requires a manual implementation of any type changes.
PUBLIC SECTION.
METHODS some_method
CHANGING some_parameter TYPE some_type.
...
ENDCLASS.
CLASS some_class IMPLEMENTATION.
METHOD some_method.
DATA save_parameter TYPE some_type.
save_parameter = some_parameter.
...
ENDMETHOD.
...
ENDCLASS.
Good Example
The following source code shows the improved declaration of the helper variable that now directly refers
to the interface parameter with LIKE, so that possible type changes are automatically accepted.
METHOD some_method.
DATA save_parameter LIKE some_parameter.
save_parameter = some_parameter.
...
ENDMETHOD.
...