# Inheritance and Polymorphism

## Inheritance:

```python
class Vehicle:
	
	vehicle_counter = 0
	
	def __init__(self, body_type, make):
		self.vehicle_body = body_type
		self.vehicle_make = make
		Vehicle.vehicle_counter += 1
		
	def get_vehicle_count(self):
		retunr Vehicle.vehicle_counter
		
class Truck(Vehicle):  
# By specifying Vehicle in parantheses the truck class iherits the propreties of the vehicle class

# So to create a truck you would use
truck1 = Truck('big rig', 'mercedes')
truck2 = Truck('small rig', 'Chevy')
truck3 = Truck('big rig', 'toyota')

truck3.get_vehicle_count # This gets the actual count of vehicles
```

* Based on the `Truck` class definition it is a `Vehicle`
* This increments the `Vehicle` counter accordingly
* `Truck` class must be used the same way as specified in the constructor of the `Vehicle` class
* `Truck` class inherits the `Vehicle` functionality

## Polymorphism (or Method Overwriting):

```python
class Vehicle:
	
	vehicle_counter = 0
	
	def __init__(self, body_type, make):
		self.vehicle_body = body_type
		self.vehicle_make = make
		Vehicle.vehicle_counter += 1
		
	def get_vehicle_count(self):
		retunr Vehicle.vehicle_counter
	
	def drive(self):
		print('vehicle driving...')

class Truck(Vehicle): # Inherits the Vehicle functionality
	def drive(self): # Overwrites the drive method from the Vehicle class
		print("Truck driving...") # By overwriting this prints specific instanced message instead
```

* The `Truck` class is also called a `child-class` or a `sub-class` of a `class`
* The `Vehicle` class is also called a `base-class` or a `parent-class`