Notes

Inside method implementation if we are using only class variables (static variables), then such type of methods we should declare as class method.

⚽ We can declare class method explicitly by using @classmethod decorator.

⚽ For class method we should provide cls variable at the time of declaration

⚽ We can call classmethod by using classname or object reference variable.

# Static Methods:

⚽ In general these methods are general utility methods.

⚽ Inside these methods we won't use any instance or class variables.

⚽ Here we won't provide self or cls arguments at the time of declaration.

⚽ We can declare static method explicitly by using @staticmethod decorator

⚽ We can access static methods by using classname or object reference

# Part -II (composition)
# using one clas member inside another class
# composition
import time
class Engine:
etype="four stroke"
def __init__(self):
self.company="tata"
def __del__(self):
print("releasing all engine resources")
def detail(self):
print("engine functionality")
class Car:
def __init__(self):
self.engine=Engine()
def __del__(self):
print("releasing all car resources")
time.sleep(3)
def car_detail(self):
self.engine.detail()
print(self.engine.etype)

c=Car()
c.car_detail()
del c


# aggregation
class Car:
def __init__(self,name,color):
self.name=name
self.color=color
def __del__(self):
print("car is releasing resources")
def car_info(self):
print(self.name,self.color)
class Emp:
def __init__(self,name,add,car):
self.name=name
self.add=add
self.car=car
def __del__(self):
print("emp release")
def emp_car_info(self):
self.car.car_info()

c=Car("TUV","black")
emp=Emp("rahul","vidisha",c)
emp.emp_car_info()
del emp
c.car_info()