How To Fix OO165 - You cannot specify a generic type for public attributes

SAP Error Message - Details

• Message type: E = Error

• Message class: OO - Class Builder/API

• Message number: 165

• Message text: You cannot specify a generic type for public attributes

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Smart SAP Assistant

• What is the cause and solution for SAP error message OO165 - You cannot specify a generic type for public attributes ?

  The SAP error message OO165, which states "You cannot specify a generic type for public attributes," typically occurs in ABAP Object-Oriented programming when you attempt to define a public attribute in a class with a generic type. In ABAP, generic types (like TYPE ANY or TYPE REF TO DATA) cannot be used for public attributes because they do not provide a specific type that can be used outside the class.
  Cause:
  The error arises when you define a public attribute in a class with a generic type. For example, if you have a class definition like this:
  CLASS my_class DEFINITION.
    PUBLIC SECTION.
      DATA my_attribute TYPE REF TO DATA. " This will cause OO165
    PRIVATE SECTION.
      DATA my_private_attribute TYPE REF TO my_type.
  ENDCLASS.
  In this case, my_attribute is defined with a generic type, which is not allowed for public attributes.
  Solution:
  To resolve this error, you need to specify a concrete type for the public attribute instead of using a generic type. Here are a few approaches you can take:
  
  
  Use a Specific Type: Change the type of the public attribute to a specific type that is known at compile time.
  CLASS my_class DEFINITION.
    PUBLIC SECTION.
      DATA my_attribute TYPE my_specific_type. " Use a specific type
    PRIVATE SECTION.
      DATA my_private_attribute TYPE REF TO my_type.
  ENDCLASS.
  
  
  Use a Generic Interface: If you need to maintain some level of flexibility, consider using a generic interface or a base class that can be referenced instead of a generic type.
  INTERFACE my_interface.
    METHODS my_method.
  ENDINTERFACE.
  
  CLASS my_class DEFINITION.
    PUBLIC SECTION.
      DATA my_attribute TYPE REF TO my_interface. " Use an interface
    PRIVATE SECTION.
      DATA my_private_attribute TYPE REF TO my_type.
  ENDCLASS.
  
  
  Use Protected Attributes: If the attribute does not need to be public, consider changing its visibility to PROTECTED or PRIVATE.
  
  
  Related Information:
  
  ABAP Documentation: Refer to the official SAP documentation for more details on data types and object-oriented programming in ABAP.
  Best Practices: When designing classes, it's a good practice to define attributes with specific types to ensure type safety and clarity in your code.
  Error Handling: Always check for similar error messages when working with object-oriented programming in ABAP, as they can provide insights into type-related issues.
  
  By following these guidelines, you should be able to resolve the OO165 error and improve the design of your ABAP classes.