How To Fix OL666 - Inheritance is not possible for interfaces

SAP Error Message - Details

• Message type: E = Error

• Message class: OL - Workflow object types: Run-time system

• Message number: 666

• Message text: Inheritance is not possible for interfaces

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message OL666 - Inheritance is not possible for interfaces ?

  The SAP error message OL666, which states "Inheritance is not possible for interfaces," typically occurs in the context of ABAP programming when there is an attempt to use inheritance with interfaces in a way that is not allowed by the ABAP language rules.
  Cause:
  
  Incorrect Inheritance Attempt: The error usually arises when you try to inherit from an interface in a manner that is not supported. In ABAP, interfaces cannot inherit from other interfaces in the same way that classes can inherit from other classes.
  Misunderstanding of Interface Behavior: Developers may mistakenly believe that interfaces can be extended or inherited like classes, which is not the case in ABAP.
  
  Solution:
  
  Check Interface Definitions: Review the interface definitions to ensure that you are not trying to inherit from another interface. Instead, you should implement multiple interfaces in a class if needed.
  Use Composition Instead of Inheritance: If you need to share functionality, consider using composition (i.e., including instances of other classes or interfaces) rather than inheritance.
  Implement Interfaces Correctly: Ensure that your class implements the interface correctly without trying to extend it. Use the INTERFACES keyword in your class definition to implement the desired interfaces.
  
  Related Information:
  
  ABAP Interface Basics: Understand that interfaces in ABAP are used to define a contract for classes. They can contain method signatures but do not contain any implementation.
  Documentation: Refer to the official SAP documentation on ABAP interfaces for more detailed information on how to properly use interfaces and the rules governing their use.
  SAP Community: Engage with the SAP Community or forums for additional insights and examples from other developers who may have encountered similar issues.
  
  By following these guidelines, you should be able to resolve the OL666 error and correctly implement your interfaces in ABAP.