OOPS-ABAP

Hyderabad February 24-26th 2009

Hyderabad February 24-26th 2009

Instructor: Subhas Katikala.

Instructor: Subhas Katikala.

Object Oriented ABAP

Workshop Goals

Workshop Goals

Th

Th

is works

is works

op will enable you to:

op will enable you to:

 _{LLearn earn objeobject ±ct ± orieoriented cnted conceoncepts.pts.}

 _{LLearn tearn thhe prie principnciple of ole of objecbject -t - orienorientedted}

programming. programming.

 _{LLearn tearn thhe application of objecte application of object}

Workshop Goals

Workshop Goals

Th

Th

is works

is works

op will enable you to:

op will enable you to:

 _{LLearn earn objeobject ±ct ± orieoriented cnted conceoncepts.pts.}

 _{LLearn tearn thhe prie principnciple of ole of objecbject -t - orienorientedted}

programming. programming.

 _{LLearn tearn thhe application of objecte application of object}

C

Course

ourse C

Contents

ontents

O

O_bjectbject OO_{riented Conceptsriented Concepts} O

O_bjectbject OO_{riented Programming.riented Programming.}

 Advantages of the

 Advantages of the OO_bject-bject-OO_{riented Approachriented Approach}

M

Metethhodsods

 _{Syntax and VisibilitySyntax and Visibility}

 _{Instance Methods and Static MethodsInstance Methods and Static Methods}  _{Constructor Constructor} 

Reference

Reference VariVariablesables

 _{Creating ReferencesCreating References}  _{Assigning References Assigning References}

Classes Classes Components of a Class Components of a Class Attributes Attributes

 _{Syntax and VisibilitySyntax and Visibility}

Course Contents

Inheritance

 Super classes and Subclasses

 Visibility

 Inheritance and the (Instance) Constructor 

 Parameters

 Redefining Methods in OO ABAP

 Compatibility

 Principles of the Narrowing Cast

 Static and Dynamic Components

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

Course Contents

Events

 Define and Trigger Events

 Handle Events

 Register and deregister Events

Object ² Oriented Concepts

at are Objects ?

 Objects are an abstraction of the real world

 Objects are units made up of data and of the functions belonging to that data

Real world Model Data MMetethhodod Method Data MMetethhodod Method Data MMetethhodod Method Boat Data MMetethhodod Method

Object Oriented Programming

OOPS

Ad

antages

 _Simplicity  _Explicitness  _{Maintainability}

 _{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.

 Y_{ou define global classes and interfaces in the Class}

Builder (Transaction SE24) in the ABAP Workbench.

 _{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.

Defining

ocal Classes

  _{A complete class definition consists of a declaration part and, if required, an}

implementation part.

 _{The declaration part of a class <class> is a statement block:} CLASS c1 DEFINITIO_N.

«.

ENDCLASS.

 _{If you declare methods in the declaration part of a class, you must also write an}

implementation part for it.

CLASS c1 IMPLEMENTATIO_N.

«.

ENDCLASS.

Defining

ocal Classes

 _{Inheritance allows you to derive a new class from an existing class.}  Y_{ou do this using the INHERITING FR}O_{M addition in the}

CLASS <subclass> DEFINITIO_{N INHERITING FR}O_{M <superclass>}

statement.

 _{The new class <subclass> inherits all of the components of the existing}

class <superclass>.

 _{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.}

R_{elationships between super classes and subclasses}

R_{elationships between super classes and}

W

idening t

e Cast



_{Interfaces exclusively describe the external point}

of contact of a class, but they do not contain their 

own implementation part.

 _{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.

 _{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. O_{bviously 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.

 _{In the above example, one class is implementing several}

interfaces.Even if these interfaces contain components with the

same name, they are differentiated in the class carrying out the

implementation by the prefix ³<interfacename>~´.

P



 OO_{bjects or Classes use events to bjects or Classes use events to trigger Event Handler methods intrigger Event Handler methods in}

other objects or classes.

other objects or classes.



 _{When an event is triggered any When an event is triggered any number of Event Handler Methods cannumber of Event Handler Methods can}

be called.

be called.



 _{The events of a class can be raised in the The events of a class can be raised in the same class using thesame class using the RAISERAISE} EVENT

EVENT Statement.Statement.



 _{Events have only output parameters which are accepted by Events have only output parameters which are accepted by the Eventthe Event}

Handler Methods as input parameters.

Handler Methods as input parameters.



 _{The link between the trigger and the handler is established dynamicallyThe link between the trigger and the handler is established dynamically}

at runtime using the statement

at runtime using the statement SET HANDLERSET HANDLER..

Events

Events

Events

Triggering and handling Events : Overview

R_{egistration/Deregistration :} H_andler