OOPs Part_03
============

Instance Variables:
===================
==> also called as "Object level variables"
==> the variables of the class can differ from object to object are called as "Instance Variables".
==> Instance variables always access with/through object only.

Ex: 
class MyClass:
	def __init__(self,a,b):
		self.a = a
		self.b = b

mc1 = MyClass(100,200)
mc2 = MyClass(1000,2000)

print("a = ")
print(mc1.a)
print(mc2.a)

print("b = ")
print(mc1.b)
print(mc2.b)

Where we can declare Instance Variables:
========================================

class MyClass:
    # instance variables can declare inside the constructor
    def __init__(self):
        self.name = "Rajesh"
        self.age = 24
    
    # we can define in the class method
    
    def definitionMethod(self):
        self.a = 123    # local variable
        self.b = 123-23.4j

# we can add instance variable to the class from outside the class also by using the object.

mc1 = MyClass()

mc1.p = 1234
mc1.mobile = 8977029779

print("The Data of the class is = ")
print(mc1.name,mc1.age)
mc1.definitionMethod()
print(mc1.a,mc1.b)
print(mc1.p)
print(mc1.mobile)

Note:
=====
When the local variable and instance variable with same name, there is a name conflict.
==> To overcome this, instance variable always define with "self" keyword.

class Car:
    def __init__(self,brand,color, maxSpeed):
        self.brand = brand
        self.color = color
        self.maxSpeed = maxSpeed
        
    def displayDetails(self):
        print(f"Brand Name : {self.brand},Color of the Brand : {self.color} and Maximum Speed : {self.maxSpeed}\n")


car1 = Car("Toyota","Red",180)
car2 = Car("Honda","Blue",200)

car1.displayDetails()
car2.displayDetails()
===============================================================
Static Variables:
=================
==> also called as "Class Level Variables".
==> can always access with the class name or object name
but prefer with class name only.
==> The value of static variable can be fixed from object to object.
Note:
====
No instance variable inside the class can define directly (without the constructor/method).
But we can define the static variable inside the class directly without any keyword like "self" or class name.

class MyClass:
    # static variable can define in the class directly
    # self.name = "Ravi"  # instance variable
    age = 30    # static variable
    
    # define the static variable inside the constructor.
    def __init__(self):
        MyClass.a = 1221
        
    # static variable can also define inside the method
    def method(self):
        MyClass.x = "Python is Awesome"
    @staticmethod
    def staticMethod():
        MyClass.p = "Python"
        # self.p1 = 1122
    
    @classmethod
    def classMethod(cls):
        MyClass.d = 101
        cls.e = 121
        # self.e1 = 11223
        
    
mc = MyClass()
# print(mc.name)
print(MyClass.age)
print(MyClass.a)
print(mc.a)
mc.method()
print(MyClass.x)
MyClass.staticMethod()
print(MyClass.p)
# print(self.p1)
MyClass.classMethod()
print(MyClass.d)
print(MyClass.e)
# print(self.e1)
===================================================
class Employee:
    employeeCount = 0   # static variable
    def __init__(self,name,position):
        self.name = name
        self.position = position
        Employee.employeeCount += 1

    def displayDetails(self):
        return f"Name : {self.name} Position : {self.position}"

emp1 = Employee("Dinesh","Auotmation Test Engineer")
emp2 = Employee("Keerthana","Software Engineer")
emp3 = Employee("Rakesh","Sr.Software Developer")

print(emp1.displayDetails())
print(emp2.displayDetails())
print(emp3.displayDetails())

print("The Total Number of Employees = ",Employee.employeeCount)
================================================================
Static Method:
=============
==> static method is class level method
==> we can call the static method using the class name only.

Ex:
BankingApplication:
	withdraw:
		same for any type of customer
			Savings Customer
			Current Customer

class DiscountCalculation:
    # static variable
    discountRate = 0.10

    # static method
    @staticmethod
    def calculateDiscountedPrice(originalPrice):
        if originalPrice < 0:
            raise ValueError("Price Cannot be Negative.")
        return originalPrice - (originalPrice * DiscountCalculation.discountRate)

originalPrice = 1000
discountedPrice = DiscountCalculation.calculateDiscountedPrice(originalPrice)
print("The Discounted Price = ",discountedPrice)
====================================================================

Class Method:
============
class Car:
    totalCars = 0
    def __init__(self,brand, model, year):
        self.brand = brand
        self.model = model
        self.year = year

    @classmethod
    def fromString(cls,carInfo):
        brand, model, year = carInfo.split(",")
        cls.totalCars+=1
        return cls(brand,model,int(year))

    @classmethod
    def carsProduced(cls):
        return f"Total Cars produced : {cls.totalCars}"

car1 = Car.fromString("Toyota,Corolla,2023")
car2 = Car.fromString("Honda, Civic,2024")

print(Car.carsProduced())
print(f"Car1:{car1.brand} {car1.model} {car1.year}")
print(f"Car2:{car2.brand} {car2.model} {car2.year}")