OOP Basics

Course: CSCI 1250

Classes

• A layout for creating objects
• Contains attributes (data) & methods (functions)
• Attributes & methods are accessed within the class using the self keyword in Python

Methods

• Functions that are inside of a class
• Can access the data of the class via self

Constructors

• Function that is ran when the class is instantiated
• In Python, defined with the __init__ method
  • C# defines with the name of the class

class Person:
	def __init__(self, name, age):
		self.name = name
		self.age = age
 
	def say_hello():
		print(f"Hello {self.name}!")

Data Classes

• A special type of class to store data
• Created with the @dataclass decorator
  • This automatically creates the __repr__ method
• Equality based on data rather than object identity
• Simple, immutable data structures without behavior (although you can add methods)

from dataclasses import dataclass
 
@dataclass # or @dataclass(frozen=True) for immutability
class Point:
	x: int
	y: int
 
# without data classes
class Point:
	def __init__(self, x, y):
		self.x = x
		self.y = y
 
	def __repr__(self):
		return f"Point(x={self.x}, y={self.y})"