Python programming : Abstract classes interfaces
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This document discusses abstract classes and interfaces in Python. It provides examples of using abstract methods and abstract classes to define common behavior for subclasses while allowing subclasses to provide their own specific implementations. Interfaces are defined as abstract classes that contain only abstract methods, allowing subclasses to fully implement the interface. Concrete methods can also be defined in abstract classes to provide shared behavior across subclasses.
![Interfaces
Program-1
from abc import *
class Myclass(ABC):
@abstractmethod
def connect(self):
pass
@abstractmethod
def disconnect(self):
pass
#Define Database
class Database:
str = input("Enter the database name: ")
#Covert the string into the class name
classname = globals()[str]
#create an object
x = classname()
#Call methods
x.connect()
x.disconnect()
#Sub-Class:1
class Oracle(Myclass):
def connect(self):
print("Connecting to oracle database...")
def disconnect(self):
print("Disconnecting from oracle
database...")
#Sub-Class:2
class Sybase(Myclass):
def connect(self):
print("Connecting to sybase database...")
def disconnect(self):
print("Disconnecting from sybase
database...")](https://image.slidesharecdn.com/abstractclassesinterfaces-190509100322/85/Python-programming-Abstract-classes-interfaces-14-320.jpg)
![Interfaces
Program-2
from abc import *
class Myclass(ABC):
@abstractmethod
def putdata(self, text):
pass
@abstractmethod
def disconnect(self):
pass
#Define Printer
class Printer:
str = input("Enter the printer name: ")
#Covert the string into the class name
classname = globals()[str]
#create an object
x = classname()
#Call methods
x.putdata("Sending to printer")
x.disconnect()
#Sub-Class:1
class IBM(Myclass):
def putdata(self, text):
print(text)
def disconnect(self):
print("Disconnecting from IBM printer...")
#Sub-Class:2
class Epson(Myclass):
def putdata(self, text):
print(text)
def disconnect(self):
print("Disconnecting from Epson printer...")](https://image.slidesharecdn.com/abstractclassesinterfaces-190509100322/85/Python-programming-Abstract-classes-interfaces-15-320.jpg)
Python programming : Abstract classes interfaces
- 1. Abstract Classes And Interfaces Team Emertxe
- 2. Introduction
- 3. Introduction Example: To understand that Myclass method is shared by all objects class Myclass: def calculate(self, x): print("Square: ", x * x) #All objects share same calculate() method obj1 = Myclass() obj1.calculate(2) obj2 = Myclass() obj2.calculate(3) obj3 = Myclass() obj3.calculate(4)
- 4. Question What If? Object-1 wants to calculate square value Object-2 wants to calculate square root Object-3 wants to calculate Cube
- 5. Solution-1 Define, three methods in the same class calculate_square() calculate_sqrt() calculate_cube() Disadvantage: All three methods are available to all the objects which is not advisable
- 6. Solution-2 calculate(x): no body calculate(x): square of x calculate(x): sqrt of x calculate(x): cube of x Obj1 Obj2 Obj3 Myclass Sub1 Sub2 Sub3
- 7. Abstract Method and Class
- 8. Abstract Method & Class Abstract Method - Is the method whose action is redefined in sub classes as per the requirements of the objects - Use decorator @abstractmethod to mark it as abstract method - Are written without body Abstract Class - Is a class generally contains some abstract methods - PVM cannot create objects to abstract class, since memory needed will not be known in advance - Since all abstract classes should be derived from the meta class ABC which belongs to abc(abstract base class) module, we need to import this module - To import abstract class, use - from abc import ABC, abstractmethod OR - from abc import *
- 9. Program-1 #To create abstract class and sub classes which implement the abstract method of the abstract class from abc import ABC, abstractmethod class Myclass(ABC): @abstractmethod def calculate(self, x): pass #Sub class-1 class Sub1(Myclass): def calculate(self, x): print("Square: ", x * x) Obj1 = Sub1() Obj1.calculate(2) Obj2 = Sub2() Obj2.calculate(16) Obj3 = Sub3() Obj2.calculate(3) #Sub class-2 import math class Sub2(Myclass): def calculate(self, x): print("Square root: ", math.sqrt(x)) #Sub class-3 class Sub3(Myclass): def calculate(self, x): print("Cube: ", x * x * x)
- 10. Example-2 Maruthi, Santro, Benz are all objects of class Car Registration no. - All cars will have reg. no. - Create var for it Fuel Tank - All cars will have common fule tank - Action: Open, Fill, Close Steering - All cars will not have common steering say, Maruthi uses- Manual steering Santro uses - Power steering - So define this as an Abstract Method Brakes - Maruthi uses hydraulic brakes - Santro uses gas brakes - So define this as an Abstract Method
- 11. Program-2 #Define an absract class from abc import * class Car(ABC): def __init__(self, reg_no): self.reg_no = reg_no def opentank(self): print("Fill the fuel for car with reg_no: ", self.reg_no) @abstractmethod def steering(self): pass @abstractmethod def braking(self): pass #Define the Maruthi class from abstract import Car class Maruthi(Car): def steering(self): print("Maruthi uses Manual steering") def braking(self): print("Maruthi uses hydraulic braking system") #Create the objects Obj = Maruthi(123) Obj.opentank() Obj.steering() Obj.braking()
- 12. Interfaces
- 13. Interfaces Abstract classes contains both, - Abstract methods - Concrete Methods Interfaces is also an Abstract class, but contains only - Abstract methods Plus point of Interface. - Every sub-class may provide its own implementation for the abstract methods
- 14. Interfaces Program-1 from abc import * class Myclass(ABC): @abstractmethod def connect(self): pass @abstractmethod def disconnect(self): pass #Define Database class Database: str = input("Enter the database name: ") #Covert the string into the class name classname = globals()[str] #create an object x = classname() #Call methods x.connect() x.disconnect() #Sub-Class:1 class Oracle(Myclass): def connect(self): print("Connecting to oracle database...") def disconnect(self): print("Disconnecting from oracle database...") #Sub-Class:2 class Sybase(Myclass): def connect(self): print("Connecting to sybase database...") def disconnect(self): print("Disconnecting from sybase database...")
- 15. Interfaces Program-2 from abc import * class Myclass(ABC): @abstractmethod def putdata(self, text): pass @abstractmethod def disconnect(self): pass #Define Printer class Printer: str = input("Enter the printer name: ") #Covert the string into the class name classname = globals()[str] #create an object x = classname() #Call methods x.putdata("Sending to printer") x.disconnect() #Sub-Class:1 class IBM(Myclass): def putdata(self, text): print(text) def disconnect(self): print("Disconnecting from IBM printer...") #Sub-Class:2 class Epson(Myclass): def putdata(self, text): print(text) def disconnect(self): print("Disconnecting from Epson printer...")
- 16. THANK YOU