Object-Oriented Software Engineering Chapter 1

Introduction to Object-Oriented Software Design (OOSD)

• Object-oriented software design (OOSD) utilizes object-oriented programming (OOP) principles to develop modular, reusable, and maintainable software applications.
• OOP is founded on the notion of "objects," which encase data (attributes) and procedures (methods).
• Objects are instances of classes, which act as blueprints defining shared attributes and behaviors.
• OOSD enhances program management and modification, especially in large, complex systems that require frequent updates.

Key Concepts of OOP: Classes, Objects, Attributes, Methods

• Classes: Serve as templates for creating objects, defining their properties and behaviors, functioning as user-defined data types.
• Objects: Specific instances of classes representing real-world entities, possessing unique states characterized by attributes and methods for behavior.
• Attributes: Also called properties, these data fields embody the state of an object and hold pertinent information like name, age, and color.
• Methods: Functions within a class that dictate an object's behavior and how it interacts with its data and other objects, enabling actions like calculations and data manipulation.

Procedural vs Object-Oriented Approach

• Shifting to object-oriented analysis and design signifies a fundamental change in thought processes from data structures and algorithms to objects and their relationships.
• Procedural Programming: Focuses on a sequence of instructions (procedures) acting on data; less modular due to entwined data and code.
• Object-Oriented Programming (OOP): Encapsulates data within objects, providing a modular structure that fosters better abstraction, inheritance, and polymorphism.

Comparison of Procedural and Object-Oriented Approaches

• Focus:

  • Procedural: Functions and procedures with entwined data and code.
  • OOP: Objects and interactions with encapsulated data.

• Code Reusability:

  • Procedural: Limited reuse capabilities.
  • OOP: Facilitates reuse through abstraction and inheritance mechanisms.

• Maintainability:

  • Procedural: Modifications can affect multiple code segments due to intertwined structure.
  • OOP: Keeps changes localized within objects, enhancing maintainability.

• Scalability:

  • Procedural: Difficulties arise when scaling programs due to complexity.
  • OOP: Modular structure promotes scalability through well-defined relationships.

• Real-world Modelling:

  • Procedural: Less effective for modelling real-world entities directly.
  • OOP: Aligns more closely with real-world entity modeling.