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OOSD Lecture 1-1.pptx FOR ENGINEERING STUDENTS
- 1. Prepared By Rajendra Kumar Rajouria UCER Naini,Allahabad Object Oriented System Design (KCS-054) Lecture-1
- 2. INDEX Introduction: The meaning of Object Orientation, object identity Example information hiding Polymorphism Generosity Importance of modelling Principles of modelling Object oriented modelling
- 3. Object Oriented System Design Course Outcome ( CO) CO 1 Understand the application development and analyze the insights of object oriented programming to implement application K2, K4 CO 2 Understand, analyze and apply the role of overall modeling concepts (i.e. System, structural) K2, K3 CO 3 Understand, analyze and apply oops concepts (i.e. abstraction, inheritance) K2, K3, K4 CO 4 Understand the basic concepts of C++ to implement the object oriented concepts K2, K3 CO 5 To understand the object oriented approach to implement real world problem. K2, K3
- 4. A Brief History The object-oriented paradigm took its shape from the initial concept of a new programming approach, while the interest in design and analysis methods came much later. The first object–oriented language was Simula (Simulation of real systems) that was developed in 1960 by researchers at the Norwegian Computing Center. In 1970, Alan Kay and his research group at Xerox PARK created a personal computer named Dynabook and the first pure object-oriented programming language (OOPL) - Smalltalk, for programming the Dynabook.
- 5. Object-Oriented Analysis Grady Booch has defined OOA as, “Object-oriented analysis is a method of analysis that examines requirements from the perspective of the classes and objects found in the vocabulary of the problem domain”.
- 6. In the 1980s, Grady Booch published a paper titled Object Oriented Design that mainly presented a design for the programming language, Ada. In the ensuing editions, he extended his ideas to a complete object– oriented design method. In the 1990s, Coad incorporated behavioral ideas to object-oriented methods.
- 7. The meaning of Object Orientation Think of objects as real-life entities. For instance, a car can be an object with properties like color, model, speed, and actions like accelerating and braking. In OOP, we encapsulate these properties and actions into a class entity. Classes serve as blueprints for creating objects. Object-oriented programming (OOP) is a computer programming model that organizes software design around data, or objects, rather than functions and logic. An object can be defined as a data field that has unique attributes and behavior. Once an object is known, it is labeled with a class of objects that defines the kind of data it contains and any logic sequences that can manipulate it. Each distinct logic sequence is known as a method. Objects can communicate with well-defined interfaces called messages.
- 8. The structure, or building blocks, of object-oriented programming include the following: Classes are user-defined data types that act as the blueprint for individual objects, attributes and methods. Objects are instances of a class created with specifically defined data. Objects can correspond to real-world objects or an abstract entity. When class is defined initially, the description is the only object that is defined. Methods are functions that objects can perform. They are defined inside a class that describe the behaviors of an object. Each method contained in class definitions starts with a reference to an instance object. Additionally, the subroutines contained in an object are called instance methods. Programmers use methods for reusability or keeping functionality encapsulated inside one object at a time. Attributes represent the state of an object. In other words, they are the characteristics that distinguish classes. Objects have data stored in the attributes field. Class attributes belong to the class itself and are defined in the class template.
- 9. Object identity Object identity: An object retains its identity even if some or all of the values of variables or definitions of methods change over time. Object identity is a property of data that is created in the context of an object data model, where an object is assigned a unique internal object identifier. Object identity is a stronger notion of identity than typically found in programming languages or in data models not based on object orientation. Several forms of identity: value: A data value is used for identity (e.g., the primary key of a tuple in a relational database). Object identity is typically implemented via a unique, system-generated OID. The value of the OID is not visible to the external user, but is used internally by the system to identify each object uniquely and to create and manage inter-object references.
- 10. Class A class represents a collection of objects having same characteristic properties that exhibit common behavior. It gives the blueprint or description of the objects that can be created from it. Creation of an object as a member of a class is called instantiation. Thus, object is an instance of a class.
- 11. Encapsulation Object-Oriented Programming (OOP) is commonly used to develop complex software systems. It is a programming paradigm based on the concept of “objects” that provides an organized approach to solving problems by breaking down a system into smaller, more manageable objects. These objects can represent real- world entities or abstract concepts. Encapsulation is a key concept in OOP. This concept involves combining data and the methods that operate on it into single unit, called as class. Encapsulation creates a layer that protects data from accidental modification, enhances code organization, and streamlines interaction between program components. Consider a car. The car body contains the engine, transmission, and brakes. You can interact with the car using its controls (steering wheel, accelerator, and brake pedal), but you don’t need to understand how they function. This is similar to the way encapsulation works in programming.
- 12. How Encapsulation Works To achieve encapsulation, you typically: Declare data members as private: This restricts direct access to the data from outside the class. Provide public methods (getters and setters): These methods act as intermediaries, allowing controlled access to the data. Getters retrieve data values, while setters modify them. Implement data validation: Within the setter methods, you can validate data before assigning it to the object’s properties, ensuring data integrity.
- 13. The Benefits of Encapsulation Data Protection: By making data private, you prevent accidental or intentional modification from outside the class, ensuring data integrity. Increased Security: Encapsulation helps protect sensitive information by restricting access to it. Code Reusability: Encapsulated classes often boast greater reusability because they function as self-contained units with clearly defined interfaces. Improved Maintainability: Changes to the internal implementation of a class are less likely to affect other parts of the program due to encapsulation.
- 14. Two Important property of Encapsulation Data Protection: Encapsulation protects the internal state of an object by keeping its data members private. Access to and modification of these data members is restricted to the class’s public methods, ensuring controlled and secure data manipulation. Information Hiding: Encapsulation hides the internal implementation details of a class from external code. Only the public interface of the class is accessible, providing abstraction and simplifying the usage of the class while allowing the internal implementation to be modified without impacting external code.
- 15. Features of Encapsulation We can not access any function from the class directly. We need an object to access that function that is using the member variables of that class. The function which we are making inside the class must use only member variables, only then it is called encapsulation. If we don’t make a function inside the class which is using the member variable of the class then we don’t call it encapsulation. Encapsulation improves readability, maintainability, and security by grouping data and methods together. It helps to control the modification of our data members.
- 16. How to Create Class in C++ class MyClass { // The class public: // Access specifier int myNum; // Attribute (int variable) string myString; // Attribute (string variable) };
- 17. How to Create Object in C++ int main() { MyClass myObj; // Create an object of MyClass // Access attributes and set values myObj.myNum = 15; myObj.myString = "Some text"; // Print attribute values cout << myObj.myNum << "n"; cout << myObj.myString; return 0; }
- 18. The constituents of a class are A set of attributes for the objects that are to be instantiated from the class. Generally, different objects of a class have some difference in the values of the attributes. Attributes are often referred as class data. A set of operations that portray the behavior of the objects of the class. Operations are also referred as functions or methods.
- 19. Example Let us consider a simple class, Circle, that represents the geometrical figure circle in a two– dimensional space. The attributes of this class can be identified as follows − x–coord, to denote x–coordinate of the center y–coord, to denote y–coordinate of the center a, to denote the radius of the circle
- 20. Some of its operations can be defined as follows − findArea(), method to calculate area findCircumference(), method to calculate circumference scale(), method to increase or decrease the radius
- 21. During instantiation, values are assigned for at least some of the attributes. If we create an object my_circle, we can assign values like x-coord : 2, y-coord : 3, and a : 4 to depict its state. Now, if the operation scale() is performed on my_circle with a scaling factor of 2, the value of the variable a will become 8. This operation brings a change in the state of my_circle, i.e., the object has exhibited certain behavior.
- 22. Objects can be modelled according to the needs of the application. An object may have a physical existence, like a customer, a car, etc.; or an intangible conceptual existence, like a project, a process, etc.