Extend interface of overridden method in ABAP

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As it commonly known, one cannot extend or redefine interface of the overridden method in the inherited ABAP class. Help:

The interface and the category of the method (a general or functional instance method or event handler) are not changed in a redefinition.

This covers both global and local classes redefinition.

What are the probable workarounds of this limitation if one wants to add or remove methods parameters or change their type? Optional parameters is a way, though not very comfy. Any other ways?

redefinition abap methods overriding
2 Answers

You cannot change the signature of an interface method in any way in its implementations. This is simply because there is no way to do this that would not produce hard-to-analyze syntax errors at run time. An interface is a contract - any class implementing it promises that it will implement all methods (and variables...) that are present in the interface.

Assume there is a method METH of interface IF1 taking a single parameter PAR1 of type TYPE1. If you now write a class that implements a method METH with a single parameter PAR1 of type TYPE2, then you have not written a class that implements IF1. A caller that passes a parameter of type TYPE1 to the method of your class will encounter a type conversion error (whether at runtime or at compile time depends somewhat on the genericity of the types).

Therefore, there is no way to change the signature of an interface method in its redefinition without producing such runtime errors - your class does not implement the interface. Implementing an interface means that the class will accept exactly the number, type and kind of parameters specified for the methods in the interface. There is literally no use case in which you could meaningfully want to change this while still claiming that your class implements the interface. Whatever you're trying to do, this isn't the solution.

user_39298570

You can create your own interface, extending the existing interface. Add same method with different parameters. Then create abstract class from your extended interface and fill methods with code for calling real method with setting values to optional parameters. After then create your class from abstract.

interface
|--> extented interface
     |--> abstract class
          |--> class
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