Informix Error -4057: A class cannot be derived from a class with PRIVATE intrinsic functions.

Cause and resolution

A class cannot be derived from a class with PRIVATE intrinsic functions.

This statement declares a new class with a DERIVED FROM clause. However, the specified base class has one or more intrinsic functions (class constructor, function such as !copy()) that are declared PRIVATE. The intrinsic functions of a base class must be available for calling from within the same functions of the derived class. Private members cannot be called so; therefore, you cannot derive a class from a base class with private intrinsic functions. Make sure that you specified the correct base class, and review its declaration.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-4057 fires when a DERIVED FROM clause names a base class whose intrinsic functions (the constructor, or a function like !copy()) are declared PRIVATE — per the official guidance, a derived class's own intrinsic functions must be able to call the base class's intrinsic functions, which PRIVATE access prevents.

The specified base class has one or more PRIVATE intrinsic functions, per the official guidance — the direct, only cause.

Solutions / Resolution

Make sure the correct base class was specified, per the official guidance.
Review the base class's declaration and change its intrinsic functions' access level if inheritance is genuinely intended, per the official guidance.

Examples

Deriving from a class with a PRIVATE constructor

CLASS Base
  FUNCTION PRIVATE Base()
    ...
  END FUNCTION
END CLASS

CLASS Derived DERIVED FROM Base
-- -4057: Base's constructor is PRIVATE
  ...
END CLASS

Corrected

CLASS Base
  FUNCTION PROTECTED Base()
    ...
  END FUNCTION
END CLASS

Diagnostic Checks

Check the intended base class's intrinsic functions for PRIVATE access, and confirm the correct base class was named, or adjust its access level.

Related Errors / Related Topics

No closely related error codes are cross-referenced for -4057 in this set yet.

The intended base class has PRIVATE intrinsic functions, which a derived class can't call — confirm the base class or adjust its access level.