CODEWITHSUNDEEP
oopinterfaceabap
RaTiO
RaTiO

Reputation: 1049

Is it correct to declare types/attributes in an interface from OOP point of view?

Is it correct to define a type within an interface? And what about an attribute?

Some programming languages only allow method signatures for an interface, but in ABAP I was considering doing something like the code below, even adding more attributes, and I'm not sure if the approach is a correct OOdesign:

INTERFACE zif_notif_note.
  TYPES: BEGIN OF ty_note_id,
           notif_num    TYPE qmnum,
           activity_key TYPE aknum,
         END OF ty_note_id.
  DATA: id TYPE ty_note_id READ-ONLY.
  METHODS get_id
    RETURNING VALUE(r_id) TYPE ty_note_id.
 ENDINTERFACE.

What if I need to use this type as an input parameter for another class? Should I better define DDIC structure then?

Upvotes: 3

Views: 1673

Answers (1)

Jagger
Jagger

Reputation: 10524

To your first question: nothing speaks against defining a type in an interface.

To your second question...

You can do many things in ABAP OO that you cannot do in other object oriented languages like Java or C++. For example you can define a FINAL ABSTRACT CLASS which is nonsense, you can define static methods (CLASS-METHODS) in an interface which is in my opinion a heresy towards the object oriented programming.

I have never defined attributes unless they were CONSTANTS within an interface, because there is no reason for doing it. They will be automatically marked as PUBLIC which breaks in fact the encapsulation principle.

So the answer would be: It is possible but think twice before going that way because it might be breaking the encapsulation of the classes that implement the interface.

Upvotes: 2

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