ABAP Keyword Documentation → ABAP - Reference → Declarations → Declaration Statements → Classes and Interfaces → ABAP Objects - Overview → Classes → Components of Classes → Constructors of Classes
Visibility of Instance Constructors
For technical reasons, the system declares the instance constructor of a class in a
visibility area;
it is therefore theoretically visible to the appropriate users. However, an instance constructor is
only executed during the creation of an object of this class using CREATE OBJECT.
Therefore the instance constructor is only visible to those users of a class that can also create objects of this class.
The additions CREATE PUBLIC|PROTECTED|PRIVATE of the statement
CLASS determine whether every user, only the heirs, or just the class
itself can create objects of the class. This means that these additions define the actual visibility of the instance constructor. Therefore the following applies:
- The instance constructor of a class defined using
CREATE PUBLICcan be called by any user.
- The instance constructor of a class defined using
CREATE PROTECTEDcan only be called by the class itself and its subclasses.
- The instance constructor of a class defined using
CREATE PRIVATEcan only be called by the class itself.
This has the following important consequence:
If a class was defined using CREATE PRIVATE, only the class itself can instantiate
itself. Subclasses of this class cannot even instantiate themselves, because they would have to call
the superclass constructor using CALL super->constructor (also see
Inheritance and Instance Creation).