OO ABAP – Interfaces and Polymorphism

May 2, 2016March 18, 2016 by Carlos Mendoza

Interfaces are simply superclasses that cannot be instantiated, do not have an implementation part, and only have public components.
This video will teach you how to define and implement interfaces to use polymorphism in ABAP.

Interfaces

The only real difference between interfaces and inheritance is the role they play. The programming advantages are thus the same as for inheritance.
Interfaces differ from regular inheritance in their area of use. In terms of programming, there are hardly any differences, however.
From a technical point of view, interfaces are simply superclasses that:
- cannot be instantiated,
- do not have an implementation part,
- and only have public components
In ABAP Objects, interfaces primarily serve to define uniform interfaces for services.
Interfaces contain no implementations.
In ABAP Objects, the same components can generally be defined in interfaces and in classes.

Use of Interfaces

Some typical use cases of interfaces are:
- You want to allow for the option of having multiple classes implementing a service in different
  ways, but using the same method names.
  - With regular inheritance, you would define such a method in the shared superclass. However, if you cannot model a superclass suitably for inheritance, you need to define an interface and then define this method there.
- Classes implement interfaces as follows:
  - The interface name is listed in the definition part of the class with the INTERFACES statement. This must be in the PUBLIC SECTION, that is, interfaces can only be implemented publicly.
  - The interface methods must be implemented in the implementation part of the class.
  - The components defined in the interface can be addressed in the implementation part of the class.

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Preview – OO ABAP: Inheritance & Casting

May 2, 2016March 11, 2016 by Carlos Mendoza

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Inheritance is an implementation relationship that emphasizes similarities of the classes. In this video you will learn how to create class hierarchies using ABAP Objects.
After watching this video you will be able to:
1. Define inheritance relationships between classes
2. Redefine methods
3. Understand the basics of casting

Introduction to OO Concepts

Object oriented concepts are the basic programming techniques common to all object-oriented languages.
As far as these concepts are concerned, the only difference between ABAP Objects and other languages like Java or C++ is the syntax.
You can only capitalize on the strengths of object-oriented programming if you use all of the concepts in the intended manner.

Inheritance & Casting

What is Inheritance?

Different kinds of objects often have a certain amount in common with each other.
Cars, trucks, and buses, for example, all share the characteristics of vehicles (current speed, current gear).
Yet each also defines additional features that make them different:
- For example, trucks carry cargo and have more tires than a car
- Buses carry more passengers than trucks and cars.

Inheritance: is the concept that when a class is defined, any subclass that is defined can inherit the definitions of that class.

There is no multiple inheritance in ABAP Objects. However, you can use interfaces in ABAP Objects to simulate multiple inheritance.

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OO (Object Oriented) ABAP – Introduction

November 1, 2019March 4, 2016 by Carlos Mendoza

This video is an introduction to the new ways of thinking and the related concepts of OO (Object Oriented) ABAP.

An example of encapsulating data using a function group is presented, and the advantage of using OO ABAP instead of procedural programming is demonstrated.

Introduction

Based on your existing knowledge of procedural programming with ABAP, I will explain the object-oriented approach using a Function Group.
I will illustrate one of the advantages of using object-oriented programming over procedural programming.
Let’s start by encapsulating data - a concept of the object-oriented programming mode – using a function group in ABAP.

Encapsulating Data: Speed

Function Group with functions to control the speed of a car.

FUNCTION-POOL zfg_vehicle.

*speed is a global variable

*used in the function-pool

DATA: speed TYPE i.

FUNCTION zfm_increase_speed.
ADD i_speed TO speed.

ENDFUNCTION.

FUNCTION zfm_decrease_speed.
SUBTRACT i_speed FROM speed.

ENDFUNCTION.

FUNCTION zfm_get_speed.
e_speed = speed.

ENDFUNCTION.