OOPS-ABAP

Object Oriented ABAP Hyderabad February 24-26th 2009 Instructor: Subhas Katikala.

Workshop Goals This

workshop will enable you to:



Learn



Learn the

princip principle le of objec objectt - oriented oriented programming.



Learn the

object object ± oriented oriented conce concepts. pts.

application of object

- oriented oriented ABAP ABAP..

Workshop Goals This

workshop will enable you to:



Learn



Learn the

princip principle le of objec objectt - oriented oriented programming.



Learn the

object object ± oriented oriented conce concepts. pts.

application of object

- oriented oriented ABAP ABAP..

Course Contents

Object Oriented

Concepts Object Oriented Programming.  Advantages of the Object-Oriented Approach Classes Components of a Class

Methods



Attributes  Syntax and Visibility  Instance Attributes and Static Attributes

Reference Variables Variables  Creating References  Assigning References

Syntax and Visibility  Instance Methods and Static Methods  Constructor 

Course Contents

Inheritance

Super classes and Subclasses  Visibility  Inheritance and the (Instance) Constructor   Parameters  ABAP  Redefining Methods in OO  Compatibility  Principles of the Narrowing Cast  Static and Dynamic Components  Final Classes and Methods 

Course Contents

Polymorphism  Advantages Compared to Procedural Programming  Abstract Classes and Methods  Component Namespaces in Classes

Interfaces

Defining and Implementing an Interface  Working with Interface Components  Interface References  Narrowing Cast  Widening Cast  Using Several Interfaces  Polymorphism and Interfaces  Polymorphism and Inheritance  Compound Interfaces 

Course Contents

Events

Define and Trigger Events  Handle Events  Register and deregister Events  Receive a reference from Sender  

Object ² Oriented Concepts

What Are Objects? What are Objects

? M odel

Real world

House

Tree

Data

Met hod

Data

Met hod

Met hod Met h od Met hod

Met hod

Crane

Data

Met hod Met hod

Boat

Met hod

Data

Met hod Met hod Met hod

¥ SAP AG 1999



Objects are an abstraction of t he real world



Objects are units made up of data and of t he functions belonging to that data

OOPS Object Oriented Programming  Encapsulation  Inheritance 

Polymorphism

 Instantiation  Interfacing  Events

Advantages 

Simplicity

 Explicitness  Maintainability 

Future Orientation

Classes





Classes are the central element of object-orientation.  A Class is an abstract description of an object.



Classes are templates for objects.



The attributes of objects are defined by the components of  the class, which describe the state and behavior of objects.

Classes



You



They are stored centrally in class pools in the class library in the R/3 Repository.



 All of the ABAP programs in an R/3 System can access the global classes.

define global classes and interfaces in the Class Builder (Transaction SE24) in the ABAP Workbench.

Components in a class

Classes Defining Local Classes 



 A complete class definition consists of a declaration part and, if required, an implementation part. The declaration part of a class is a statement block: CLASS c1 DEFINITION. «. ENDCLASS.



If you declare methods in the declaration part of a class, you must also write an implementation part for it. CLASS c1 IMPLEMENTATION. «. ENDCLASS.

Attributes

Classes Defining Local Classes

Attributes, Types,

Constants - Syntax

Attributes

and Visibility

Instance attributes

and Static attributes

Methods

Methods

: Syntax

Methods

and Visibility

Instance

methods and Static methods

Instance methods and

Static methods : Example

Constructor

Constructor : Example

Static Constructor : Implementation

Static Constructor : Call Examples

Creating Objects

Reference

Variables

Creating Objects : Syntax

Assigning References

Inheritance



Inheritance allows you to derive a new class from an existing class.



You

do this using the INHERITING FROM addition in the

CLASS DEFINITION INHERITING FR OM

statement. 

The new class inherits all of the components of the existing class .



The new class is called the subclass of the class from which it is derived.



The original class is called the superclass of the new class.

Inheritance

Inheritance :

Syntax

Relationships

Relationships

between super classes and subclasses

between super classes and subclasses

Inheritance and

Visibility

Inheritance

and (Instance) constructor

Parameters and CREATE OBJECT

Redefining Methods

in ABAP Objects

Redefining Methods

: Example

Compatibility and Narrowing Cast 

Principles of the Narrowing Cast 

Static and Dynamic Types: Example

Static and Dynamic Types for

References

Static and Dynamic Types for

Widening the

Cast

References

Widening the cast 

Polymorphism

Polymorphism

Polymorphism

Interface



Interfaces exclusively describe the external point of contact of a class, but they do not contain their  own implementation part.

Defining and Implementing Interface

Working with Interface components

Interface References Narrowing

casting

Interface



The assignment of an object reference to an interface reference is known as a narrowing cast since, as with inheritance, only a part of the object interface is visible once you have assigned the reference.



With an interface reference, you can no longer address all components in the class carrying out the implementation, but only the components defined in the interface.

Interface

references widening cast 

Interface





The widening cast is, as with inheritance, the opposite of the narrowing cast: here it is used to retrieve an object reference from an interface reference. Obviously it cannot be statically checked, since an interface can be implemented by more than one class.  An object reference cannot be assigned to an interface reference if it has itself not implemented the corresponding interface.

Using



several Interface

In the

above example, one class is implementing se veral interfaces. Even if these interfaces contain components wit h the same name, they are differentiated in t he class carrying out t he implementation by t he prefix ³~´.

Polymorphism and Interface

Events

    

Objects

or Classes use events to trigger Event Handler methods in other objects or classes. When an event is triggered any number of Event Handler Methods can be called. The events of a class can be raised in the same class using the RAISE EVENT Statement. Events have only output parameters which are accepted by the Event Handler Methods as input parameters. The link between the trigger and the handler is established dynamically at runtime using the statement SET HANDLER.

Events Overview

Triggering and handling Events : Overview

Defining and Triggering Events

Handling

and Registering Events

Handling Events

Registering

for an Event : Syntax

Deregistration

Registration/Deregistration

:

Handler

Table

Event handling : Characteristics