Object Oriented ABAP/4 Programming Overview - JH Softech

1. Introduction and Concepts of Object
Oriented ABAP
Vikram Aditya
SAP Architect
Email: aditya@jhsoftech.com
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2. 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).
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3. Comparison between Procedural and
Object Oriented Programming
• Features Procedure Oriented approach Object Oriented
approach Emphasis Emphasis on tasks Emphasis on
things that does those tasks.
• Modularization Programs are divided into smaller
programs known as functions Programs are organized
into classes and objects and the functionalities are
embedded into methods of a class. Data security Most
of the functions share global data Data can be hidden
and cannot be accessed by external sources.
Extensibility Relatively more time consuming to modify
for extending existing functionality. New data and
functions can be easily added whenever necessary O
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5. What is an Object ?
• 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.
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6. ABAP Objects
• 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
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7. 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
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8. 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
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9. 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:
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10. 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
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11. 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.
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12. 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
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13. 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.
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14. Uses of Object Orientation
• 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.
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15. 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 modelling
• The object-orientation modelling 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.
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16. Overview
• 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.
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17. Working with class methods in OOABAP
What is a method in a Class ?
• Methods are coding blocks of a class, which can provide
some business functionality (ex: read material data etc),
these methods are similar to Function Modules.
• Methods can access all attributes of a class (defined under
attributes tab), can access user defined types ( declared
under types tab).
• The methods can be called using key word CALL METHOD in
SAP ABAP programs.
Uses of methods in SAP classes?
• These methods can be reusable in multiple ABAP programs,
a class may contain more than one method.
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