Python Classroom notes 24/Mar/2026

Object Oriented Programming

• Mental model: Every thing is object

• Object has

  • Contents: What it has
  • Characteristics: What it can do

• Library as a system

  • Objects:
    • book:
      • characterstics:
        • rent
      • contents:
        • id
        • author
        • title
    • librarian
      • characteristics:
        • lend books
        • collect books
      • Contents:
        • username
        • emailid
    • User:
      • Characteristic:
        • rent book
        • return book
        • pay subscription
      • Contents:
        • username
        • mobileno
        • email
    • rack
      • Characteristics:
        • Find book
        • List of books
      • Contents:
        • books

Relationships between Objects

• On a broader note we have two kinds of relationships
  • Inheritence: is-a relationship
  • Composition: has-a relationship

Inheritence

• Is-a: Get parent characteristics and contents in child objects