Key Points Of OOP & Sample Code

Key Points Of Object Oriented Programming

Hi, most of the people here on SCN try to learn object oriented programming through various available sources. I have also tried a lot to learn this beautiful OOP feature and still learning it. Even I have gone through various SAP Press Books to summarize all the aspects of it. Here I have prepared a small set of information that would be useful before, after and in-between phase of learning OOP. It also helps you to get quick understanding of any topic before you go in depth. I have not explained global class here that is skipped intentionally for your practice with reference to local class. Please check all sample abap code. As I said I am also learning so I may not give you some of your queries so please bear with me and help me to improve this document so that everyone can get benefit from it. I always try to provide best details to you if possible. Thank you.

Class	A class is an abstract representation, or, a set of instructions for building objects
Object	Objects are instances of classes. There can be any number of objects or instances in a class. Each object has a unique identity and its own attributes.
Encapsulation	Visibility (public, protected, private)
Inheritance	Inheritance allows you to derive a new class from an existing class.
Polymorphism	Overriding methods / redefining method - after inheriting / Interface.
Abstract	Definition of a class cannot generate instance. You can only Use an abstract class to create subclass.
Friend-Deferred	Access private attributes of another class.
Event	Invoke methods of same or other class.
Interface	Cannot have implementation, just the definition.
Exception	Static check-(check both at runtime and compile time), Dynamic check (only checks at runtime), No check (for all kind of exceptions). using CX_ROOT class
Levels	Instance, static, Constant.
Test class / Test methods	unit test (Test method class CL_AUNIT_ASSERT, #AU_DURATION_SHORT, #AU_RISK_LEVEL HARMLESS)
Persistent Class	Agent class, Base class, Class.
Refactoring Assistant	Add new class above any existing class.
Serialization	Transformation of ABAP data in an XML document. Either by calling a XSLT program or a simple transformation. When using XSLT, the system first generates a canonical XML representation (asXML).
Object parameters	Importing/Exporting/Returning-(receiving)/Exception and Raising

Additional Points.

->Static data shares common value across any number of its object, and it is only accessible inside static method and it is accessible via => operator (cls_name=>static attribute).

->Multiple inheritance is not supported by abap (we may use interface to achieve this).

->In object parameter: Exception is non-class base exception which is triggered with statement raise / message raising.

->In object parameter: Raising is class base exception which is triggered with statement raise / message raising.

-> Protected section will become private in successor class once it is inherited from parent.

->The tilde (~) between the interface name and the interface component name is called the interface component selector operator.

->In persistent the class builder also generates a couple of additional agent classes that manage all of the low-level interaction details between objects of the persistent class and the Persistence Service.

->objects of persistent classes are referred to as managed objects.

->Transaction persistent service (We can insert data directly from persistent class to dB table using Tcode). IF_OS_TRANSACTION & IF_OS_TRANSACTION_MANAGER

->Transaction for a local class method

->XML Transformation using Tcode xslt_tool to generate xml files.

General OOP Course Content that you should know: