Object Oriented Design

 Object Oriented Design

According to wikipedia :

An object contains encapsulated data and procedures grouped together to represent an entity. The 'object interface' defines how the object can be interacted with. An object-oriented program is described by the interaction of these objects. Object-oriented design is the discipline of defining the objects and their interactions to solve a problem that was identified and documented during object-oriented analysis.

What follows is a description of the class-based subset of object-oriented design, which does not include object prototype-based approaches where objects are not typically obtained by instantiating classes but by cloning other (prototype) objects. Object-oriented design is a method of design encompassing the process of object-oriented decomposition and a notation for depicting both logical and physical as well as state and dynamic models of the system under design.

At the beginning of the computing era, programming was usually limited to machine language programming. Machine language means those sets of instructions that are specific to a particular machine or processor, which are in the form of 0’s and 1’s. These are sequences of bits (0100110…). But it’s quite difficult to write a program or develop software in machine language.

It’s actually impossible to develop software used in today’s scenarios with sequences of bits. This was the main reason programmers moved on to the next generation of programming languages, developing assembly languages, which were near enough to the English language to easily understand. These assembly languages were used in microprocessors. With the invention of the microprocessor, assembly languages flourished and ruled over the industry, but it was not enough. Again, programmers came up with something new, i.e., structured and procedural programming.

Structured Programming –

The basic principle of the structured programming approach is to divide a program into functions and modules. The use of modules and functions makes the program more understandable and readable. It helps to write cleaner code and to maintain control over the functions and modules. This approach gives importance to functions rather than data. It focuses on the development of large software applications, for example, C was used for modern operating system development. The programming languages: PASCAL (introduced by Niklaus Wirth) and C (introduced by Dennis Ritchie) follow this approach.

Procedural Programming Approach 

This approach is also known as the top-down approach. In this approach, a program is divided into functions that perform specific tasks. This approach is mainly used for medium-sized applications. Data is global, and all the functions can access global data. The basic drawback of the procedural programming approach is that data is not secured because data is global and can be accessed by any function. Program control flow is achieved through function calls and goto statements. The programming languages: FORTRAN (developed by IBM) and COBOL (developed by Dr Grace Murray Hopper) follow this approach.

These programming constructs were developed in the late 1970s and 1980s. There were still some issues with these languages, though they fulfilled the criteria of well-structured programs, software etc. They were not as structured as the requirements were at that time. They seem to be over-generalised and don’t correlate with real-time applications.

To solve such kinds of problems, OOP, an object-oriented approach was developed as a solution.

The Object-Oriented Programming (OOP) Approach 
The OOP concept was basically designed to overcome the drawback of the above programming methodologies, which were not so close to real-world applications. The demand was increased, but still, conventional methods were used. This new approach brought a revolution in the programming methodology field.

Object-oriented programming (OOP) is nothing but that which allows the writing of programs with the help of certain classes and real-time objects. We can say that this approach is very close to the real-world and its applications because the state and behaviour of these classes and objects are almost the same as real-world objects.

Let’s go deeper into the general concepts of OOP, which are given below:

Data Abstraction 
Abstraction refers to the act of representing important and special features without including the background details or explanation about that feature. Data abstraction simplifies database design.

1. Physical Level:
   It describes how the records are stored, which are often hidden from the user. It can be described with the phrase, “block of storage.”
2. Logical Level:
   It describes data stored in the database and the relationships between the data. The programmers generally work at this level as they are aware of the functions needed to maintain the relationships between the data.
3. View Level:
   Application programs hide details of data types and information for security purposes. This level is generally implemented with the help of GUI, and details that are meant for the user are shown.

Encapsulation 
Encapsulation is one of the fundamental concepts in object-oriented programming (OOP). It describes the idea of wrapping data and the methods that work on data within one unit, e.g., a class in Java. This concept is often used to hide the internal state representation of an object from the outside.

Inheritance 
Inheritance is the ability of one class to inherit capabilities or properties of another class, called the parent class. When we write a class, we inherit properties from other classes. So when we create a class, we do not need to write all the properties and functions again and again, as these can be inherited from another class which possesses it. Inheritance allows the user to reuse the code whenever possible and reduce its redundancy.

Polymorphism 
Polymorphism is the ability of data to be processed in more than one form. It allows the performance of the same task in various ways. It consists of method overloading and method overriding, i.e., writing the method once and performing a number of tasks using the same method name.