Class and Object Terms

The foundations of Object-Oriented Programming is defining a Class

In Object-Oriented Programming (OOP), a class is a blueprint for creating an Object. (a data structure). An Object is used like many other Python variables.

A Class has ...

a collection of data, these are called Attributes and in Python are pre-fixed using the keyword self

a collection of Functions/Procedures. These are called *Methods when they exist inside a Class definition.

An Object is created from the Class/Template. Characteristics of objects ...

an Object is an Instance of the Class/Template

there can be many Objects created from the same Class

each Object contains its own Instance Data

the data is setup by the Constructor, this is the "init" method in a Python class

all methods in the Class/Template become part of the Object, methods are accessed using dot notation (object.method())

A Python Class allow for the definition of @ decorators, these allow access to instance data without the use of functions ...

@property decorator (aka getter). This enables developers to reference/get instance data in a shorthand fashion (object.name versus object.get_name())

@name.setter decorator (aka setter). This enables developers to update/set instance data in a shorthand fashion (object.name = "John" versus object.set_name("John"))

observe all instance data (self._name, self.email ...) are prefixed with "", this convention allows setters and getters to work with more natural variable name (name, email ...)

Start Code for Hacks

from datetime import date

def calculate_age(born):
    today = date.today()
    return today.year - born.year - ((today.month, today.day) < (born.month, born.day))

dob = date(2004, 12, 31)
age = calculate_age(dob)
print(age)

18

class Student:
    def __init__(self, name, major, gpa, classOf):
        self.name = name
        self.major = major
        self.gpa = gpa
        self.classOf = classOf
        self.dob = None
        self.age = None

    def set_dob(self, dob):
        self.dob = dob
        self.age = self.calc_age()

    def calc_age(self):
        today = date.today()
        age = today.year - self.dob.year - ((today.month, today.day) < (self.dob.month, self.dob.day))
        return age

    def get_classOf(self):
        return self.classOf

    def get_age(self):
        return self.age


def tester():
    student1 = Student("Jim", "Business", 3.1, 2019)
    student1.set_dob(date(1994, 2, 21))
    print("Student's name is: " + student1.name)
    print("Student's class of: " + str(student1.get_classOf()))
    print("Student's age is: " + str(student1.get_age()) + " years old")

tester()

Student's name is: Jim
Student's class of: 2019
Student's age is: 28 years old

class FastFood:
    def __init__(self, name, price, ingredients):
        self.name = name
        self.price = price
        self.ingredients = ingredients
    
    # getters
    def get_name(self):
        return self.name

    def get_price(self):
        return self.price

    def get_ingredients(self):
        return self.ingredients

    # setters
    def set_name(self, name):
        self.name = name

    def set_price(self, price):
        self.price = price

    def set_ingredients(self, ingredients):
        self.ingredients = ingredients

# tester
burger = FastFood("Hamburger", 5.99, ["Bun", "Beef Patty", "Lettuce", "Tomato", "Onion"])

print(burger.get_name())
print(burger.get_price())
print(burger.get_ingredients())

burger.set_price(6.99)

print(burger.get_price())

Hamburger
5.99
['Bun', 'Beef Patty', 'Lettuce', 'Tomato', 'Onion']
6.99