Re: object oriented programming concepts

ABAP (Advanced Business Application Programming) is a programming language for developing applications for the SAP R/3 system, a widely-installed business application subsystem.

The latest version, ABAP Objects, is object-oriented programming. SAP will run applications written using ABAP/4, the earlier ABAP version, as well as applications using ABAP Objects.

SAP's original business model for R/3 was developed before the idea of an object-oriented model was widespread. The transition to the object-oriented model reflects an increased customer demand for it. ABAP Objects uses a single inheritance model and full support for object features such as encapsulation, polymorphism, and persistence.

ABAP Objects

ABAP Objects is a new concept in R/3 System and you can find its two distinct meanings --- one is for the entire ABAP runtime environment and the other represents the new object-oriented generation of this language.

The Runtime Environment

ABAP Objects, for the entire ABAP runtime environment, are an indication of how SAP has, for sometime, been moving towards object orientation. Object-oriented techniques have been used exclusively in system design. The ABAP language did not support these techniques earlier.

The ABAP Workbench will allow creating R/3 Repository objects in this regard. These objects are programs, authorization objects, lock objects, customizing objects, and so on and so forth. By using function modules, one can also encapsulate functions in separate programs with a defined lnterface. The Business Object Repository (BOR) allows you to create SAP Business Objects for internal and external use.

The Object-Oriented Language Extension

ABAP Objects support object-oriented programming. The ABAP Objects is a complete set of object-oriented statements, which has been introduced into the ABAP language. This object-oriented extension of ABAP builds on the existing language and is fully compatible with it.

The Object Orientation (OO), also known as the object-oriented paradigm, is a programming model that unites data and functions in objects. You can not only use ABAP Objects in existing programs, but also work with and use a conventional ABAP in new ABAP Objects programs. The rest of the ABAP language is primarily intended for structured programming, where data is stored in a structured form in database tables and function-oriented programs access and work with it.

Moreover, we should know that the object-oriented enhancement of ABAP is based on the models of Java and C++. It is compatible with external object interfaces such as DCOM and CORBA. The implementation of object-oriented elements in the kernel of the ABAP language has considerably increased response times when you work with ABAP Objects. Some other objects, such as SAP Business Objects and GUI objects, which are already object-oriented by themselves, are also benefiting from being incorporated into ABAP Objects.

About Classes

The classes are templates for objects. An abstract description of an object is the class. You could say it is a set of instructions for building an object. The attributes of objects are defined by the components of the class, which describe the state and behavior of objects.

Local and Global Classes

In ABAP Objects, classes can be declared either globally or locally. You define global classes and interfaces in the Class Builder (Transaction SE24.} in the ABAP Workbench. In the R/3 Repository, they are stored centrally in class pools in the class library. In an R/3 System, all of the ABAP programs can access the global classes. The local classes are defined within an ABAP program. Local classes and interfaces can only be used in the program in which they are defined. When you use a class in an ABAP program, the system first searches for a local class with the specified name. If it does not find one, then it looks for a global class. Apart from the visibility question, there is no difference between using a global class and using a local class.

However, there is a significant difference in the way that local and global classes are designed. If you are defining a local class that is only used in a single program, then to define the outwardly visible components so that it fits into that program is usually sufficient. On the other hand, global classes must be able to be used anywhere. Since the system must be able to guarantee any program using an object of a global class, it can recognize the data type of each interface parameter and then certain restrictions are applied at the time of defining the interface of a global class.

Defining Local Classes

Local classes consist of ABAP source code, where the ABAP statements CLASS...ENDCLASS are enclosed. A complete class definition consists of the following parts, a declaration part and, if required, an implementation part. It is found that the declaration part of a class

ENDMETHODIn the same way as in other ABAP procedures (subroutines and function modules), you can declare local data types and objects in methods. You call the following methods by using the CALL METHOD statement.

Instance Method

You can declare instance methods by using the METHODS statement. They play a very important role as they can access all of the attributes of a class and can trigger all of the events of the class.

For more information refer the below thread:

/thread/415717

Both the thread contains many links for learning ABAP oops.....

Please refer to the following links,

http://help.sap.com/saphelp_nw70/helpdata/en/c3/225b5654f411d194a60000e8353423/frameset.htm

http://help.sap.com/saphelp_nw04/helpdata/en/86/8280ba12d511d5991b00508b6b8b11/frameset.htm

Also if you working on ABAP mapping,refer to the following link,

http://help.sap.com/saphelp_nw04/helpdata/en/47/b5413acdb62f70e10000000a114084/content.htm

Reward if helpful.

Thanks

Jagadeesh.G

Former Member · ‎2008 May 13

Hi,

mention ur maild id, so that i can send docs.

Thanks.

Santosh.

Former Member · ‎2008 May 13

Hi,

Here are few tutorils on oops,have a look at them.

http://www.saptechnical.com/Tutorials/OOPS/MainPage.htm

Follow the link for OOPS stuff.

or download the PDF form here

http://www.esnips.com/doc/6d16a298-9227-4d32-acf1-e91164c89daf/3-ABAP-Objects(P283)

Following data and links will help you.Just have a look at it.

What is Object Orientation?

In the past, information systems used to be defined primarily by their functionality: data and functions were kept separate and linked together by means of input and output relations.

The object-oriented approach, however, focuses on objects that represent abstract or concrete things of the real world. These objects are first defined by their character and their properties which are represented by their internal structure and their attributes (data). The behaviour of these objects is described by methods (functionality).

Objects form a capsule which combines the character to the respective behaviour. Objects should enable programmers to map a real problem and its proposed software solution on a one-to-one basis.

Typical objects in a business environment are, for example, ‘Customer’, ‘Order’, or ‘Invoice’. From Release 3.1 onwards, the Business Object Repository (BOR) of SAP Web Applicaton Server ABAP has contained examples of such objects. The BOR object model will be integrated into ABAP Objects in the next Release by migrating the BOR object types to the ABAP class library.

A comprehensive introduction to object orientation as a whole would go far beyond the limits of this introduction to ABAP Objects. This documentation introduces a selection of terms that are used universally in object orientation and also occur in ABAP Objects. In subsequent sections, it goes on to discuss in more detail how these terms are used in ABAP Objects. The end of this section contains a list of further reading, with a selection of titles about object orientation.

Objects

Objects are instances of classes. They contain data and provides services. The data forms the attributes of the object. The services are known as methods (also known as operations or functions). Typically, methods operate on private data (the attributes, or state of the object), which is only visible to the methods of the object. Thus the attributes of an object cannot be changed directly by the user, but only by the methods of the object. This guarantees the internal consistency of the object.

Classes

Classes describe objects. From a technical point of view, objects are runtime instances of a class. In theory, you can create any number of objects based on a single class. Each instance (object) of a class has a unique identity and its own set of values for its attributes.

Object References

In a program, you identify and address objects using unique object references. Object references allow you to access the attributes and methods of an object.

In object-oriented programming, objects usually have the following properties:

Encapsulation

Objects restrict the visibility of their resources (attributes and methods) to other users. Every object has an interface, which determines how other objects can interact with it. The implementation of the object is encapsulated, that is, invisible outside the object itself.

Inheritance

You can use an existing class to derive a new class. Derived classes inherit the data and methods of the superclass. However, they can overwrite existing methods, and also add new ones.

Polymorphism

Identical (identically-named) methods behave differently in different classes. In ABAP Objects, polymorphism is implemented by redefining methods during inheritance and by using constructs called interfaces.

Uses of Object Orientation

Below are some of the advantages of object-oriented programming:

• Complex software systems become easier to understand, since object-oriented structuring provides a closer representation of reality than other programming techniques.

• In a well-designed object-oriented system, it should be possible to implement changes at class level, without having to make alterations at other points in the system. This reduces the overall amount of maintenance required.

• Through polymorphism and inheritance, object-oriented programming allows you to reuse individual components.

• In an object-oriented system, the amount of work involved in revising and maintaining the system is reduced, since many problems can be detected and corrected in the design phase.

Achieving these goals requires:

• Object-oriented programming languages

Object-oriented programming techniques do not necessarily depend on object-oriented programming languages. However, the efficiency of object-oriented programming depends directly on how object-oriented language techniques are implemented in the system kernel.

• Object-oriented tools

Object-oriented tools allow you to create object-oriented programs in object-oriented languages. They allow you to model and store development objects and the relationships between them.

• Object-oriented modeling

The object-orientation modeling of a software system is the most important, most time-consuming, and most difficult requirement for attaining the above goals. Object-oriented design involves more than just object-oriented programming, and provides logical advantages that are independent of the actual implementation.

This section of the ABAP User’s Guide provides an overview of the object-oriented extension of the ABAP language. We have used simple examples to demonstrate how to use the new features. However, these are not intended to be a model for object-oriented design. More detailed information about each of the ABAP Objects statements is contained in the keyword documentation in the ABAP Editor. For a comprehensive introduction to object-oriented software development, you should read one or more of the titles listed below.

ABAP supports a hybrid programming model. You can use an object-oriented ("OO") programming model based on classes and interfaces, and you can use the more classic procedural and event-driven programming model based on function modules, subroutines, dialog modules, and event blocks. Both models can be used in parallel. You can use classes inside classic processing blocks or you can call classic procedures from methods. In ABAP Objects, SAP has implemented a cleanup of the ABAP language. Within the scope of this language cleanup, stricter syntax checks are performed in classes that restrict the usage of obsolete language elements.

Object orientation in ABAP is an extension of the ABAP language that makes available the advantages of object-oriented programming, such as encapsulation, interfaces, and inheritance. This helps to simplify applications and make them more controllable.

ABAP Objects is fully compatible with the existing language, so you can use existing statements and modularization units in programs that use ABAP Objects, and can also use ABAP Objects in existing ABAP programs.

Check these links

/people/thomas.jung3/blog/2005/09/08/oo-abap-dynpro-programming

/people/ravikumar.allampallam/blog/2005/02/11/abap-oo-in-action

This is good for beginners

/people/sap.user72/blog/2005/05/10/a-small-tip-for-the-beginners-in-oo-abap

check the below links lot of info and examples r there

http://www.sapgenie.com/abap/OO/index.htm

http://www.geocities.com/victorav15/sapr3/abap_ood.html

http://www.brabandt.de/html/abap_oo.html

Check this cool weblog:

/people/thomas.jung3/blog/2004/12/08/abap-persistent-classes-coding-without-sql

http://help.sap.com/saphelp_nw04/helpdata/en/c3/225b6254f411d194a60000e8353423/frameset.htm