Object-oriented ABAP

After the object-oriented features were introduced to ABAP, it is termed as ABAP Objects. In the new language both the paradigms 'Structural' as well as 'Object-oriented' exist together. Millions of lines of code written in the earlier version of langauge exists at so many implementations and backward compatibility required to keep the earlier features intact. There are many of earlier statements marked as obsolete and documented in SAP Help and still supported but may not be supported in future SAP versions. In addition there are several statements which can't be used inside classes since there was no such compulsion of backward compatibility with the use of classes. Under the current topic, we will discuss the object-oriented features of ABAP Objects.

Basic concepts of ABAP Objects

If you are entirely new to object-oriented ABAP and need to understand the basic concepts of object-oriented programming paradigm applied to ABAP, you can refer SAP Help documentation on ABAP Objects. If you have understood basic concepts (like what are classes and methods), you can move to the next topic below.

Inheritence & Polymorphism in ABAP

For those who understand the very basic ABAP object-oriented features like Classes and Methods, we will refer to freely available Chapter 6: Advanced concepts in ABAP Objects from the SAP-Press book "ABAP Objects" from the authors Horst Keller, Sascha Krüger. It covers the topics ranging from ... Method calls ... parameter passing ... Inheritence ... Method Redefinition ... Abstract Classes and Methods ... Final Classes and Methods ... Static attributes Superclasses-subclasses ... Constructors ... Interfaces ...to ... Object references and Polymorphism.

is a great book and explains vividly the concepts taking you through the code. If any one book can be named as "must have" for SAP ABAP consultants, it is this book !!!

Another resource is the book "Object oriented programming with ABAP Objects" from James Wood whose freely available sample chapter 5 discusses Inheritence.

SAP Classes

SAP has bundled a good number of standard classes into the ECC package. Their use varies from displaying the output in ALV form ... File upload / download ... Exception Handling ...to ... Run time type identification and creation. The standard SAP classes are the most commonly used component of new ABAP Objects to achieve the desired business results and have made ABAP a powerful langauge.