The document discusses concepts of code reusability in object-oriented programming, focusing on inheritance and composition as methods to achieve this. It distinguishes between composition (strong association) and aggregation (weak association), as well as generalization and specialization. The author emphasizes the benefits of composition over inheritance due to reduced coupling and greater flexibility in class design.

1. Code Reusability
Object oriented programming styles

2. How to reuse code in a class again?
INHERITANCE
COMPOSITION

3. Before we start
 Composition Vs Aggregation
 Generalization vs Specialization
 Inheritance Vs composition

4. Association types
 Composition
 Is a strong association
 In UML diagram, composition is denoted by a
filled diamond.
 Aggregation
 Is a weak association
 In UML diagram, composition is denoted by an
empty diamond.
 Children can exist independently.

5. Composition Example

6. Aggregation Example

7. Generalization vs Specialization
 Generalization
 Is a mechanism for combining similar classes of
objects into a single, more general class.
 Specialization
 Is the reverse process of Generalization, which
means creating new sub-classes from an existing
class.

8. Generalization Example

9. Inheritance Vs
composition
 Both can help you reuse code.
 Inheritance establishes common behavior and interfaces
for your classes, while composition combines and reuses
existing classes to create more complex objects.
 Inheritance (is-a relationship), composition (has-a
relationship).
 Inheritance increases the coupling between a base type
and its derived types. If you change your base class, all
subclasses are also affected.
 prefer composition over inheritance

10. Thank you