{"id":538,"date":"2020-10-14T05:56:49","date_gmt":"2020-10-14T05:56:49","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=538"},"modified":"2025-03-31T10:11:33","modified_gmt":"2025-03-31T10:11:33","slug":"python-inheritance","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-oop\/python-inheritance\/","title":{"rendered":"Python Inheritance"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about Python inheritance and how to use the inheritance to reuse code from an existing class.<\/p>\n\n\n\n

Introduction to the Python inheritance #<\/a><\/h2>\n\n\n\n

Inheritance allows a class<\/a> to reuse the logic of an existing class. Suppose you have the following Person<\/code> class:<\/p>\n\n\n

class<\/span> Person<\/span>:<\/span>\n    def<\/span> __init__<\/span>(self, name)<\/span>:<\/span>\n        self.name = name\n\n    def<\/span> greet<\/span>(self)<\/span>:<\/span>\n        return<\/span> f\"Hi, it's {self.name}<\/span>\"<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The Person<\/code> class has the name<\/code> attribute and the greet()<\/code> method.<\/p>\n\n\n\n
Now, you want to define the Employee<\/code> that is similar to the Person<\/code> class:<\/p>\n\n\n
class<\/span> Employee<\/span>:<\/span>\n    def<\/span> __init__<\/span>(self, name, job_title)<\/span>:<\/span>\n        self.name = name\n        self.job_title = job_title\n\n    def<\/span> greet<\/span>(self)<\/span>:<\/span>\n        return<\/span> f\"Hi, it's {self.name}<\/span>\"<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The Employee<\/code> class has two attributes name<\/code> and job_title<\/code>. It also has the greet()<\/code> method that is exactly the same as the greet()<\/code> method of the Person<\/code> class.<\/p>\n\n\n\n
To reuse the greet()<\/code> method from the Person<\/code> class in the Employee<\/code> class, you can create a relationship between the Person<\/code> and Employee<\/code> classes. To do it, you use inheritance so that the Employee<\/code> class inherits from the Person<\/code> class. <\/p>\n\n\n\n
The following redefines the Employee<\/code> class that inherits from the Person<\/code> class:<\/p>\n\n\n
class<\/span> Employee<\/span>(Person)<\/span>:<\/span>\n    def<\/span> __init__<\/span>(self, name, job_title)<\/span>:<\/span>\n        self.name = name\n        self.job_title = job_title<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
By doing this, the Employee<\/code> class behaves the same as the Person<\/code> class without redefining the greet() method. <\/p>\n\n\n\n
This is a single inheritance<\/strong> because the Employee<\/code> inherits from a single class (Person<\/code>). Note that Python also supports multiple inheritances where a class inherits from multiple classes.<\/p>\n\n\n\n
Since the Employee<\/code> inherits attributes and methods of the Person<\/code> class, you can use the instance of the Employee class as if it were an instance of the Person<\/code> class. <\/p>\n\n\n\n
For example, the following creates a new instance of the Employee<\/code> class and call the greet()<\/code> method:<\/p>\n\n\n
employee = Employee('John'<\/span>, 'Python Developer'<\/span>)\nprint(employee.greet())<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Hi, it's John<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Inheritance terminology #<\/a><\/h3>\n\n\n\n
The Person<\/code> class is the parent class<\/strong>, the base class<\/strong>, or the super class<\/strong> of the Employee<\/code> class. And the Employee<\/code> class is a child <\/strong>class, a derived class<\/strong>, or a subclass <\/strong>of the Person<\/code> class.<\/p>\n\n\n\n
The Employee<\/code> class derives from<\/strong>, extends<\/strong>, or subclasses <\/strong>the Person<\/code> class.<\/p>\n\n\n\n
The relationship between the Employee<\/code> class and Person<\/code> class is IS-A<\/strong> relationship. In other words, an employee is a<\/strong> person.<\/p>\n\n\n\n
type vs. isinstance #<\/a><\/h2>\n\n\n\n
The following shows the type of instances of the Person<\/code> and Employee<\/code> classes:<\/p>\n\n\n
person = Person('Jane'<\/span>)\nprint(type(person))\n\nemployee = Employee('John'<\/span>, 'Python Developer'<\/span>)\nprint(type(employee))<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
<class<\/span> '__main__<\/span>.Person<\/span>'>\n<class<\/span> '__main__<\/span>.Employee<\/span>'><\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
To check if an object is an instance of a class, you use the isinstance()<\/code> method. For example:<\/p>\n\n\n
person = Person('Jane'<\/span>)\nprint(isinstance(person, Person))  # True<\/span>\n\nemployee = Employee('John'<\/span>, 'Python Developer'<\/span>)\nprint(isinstance(employee, Person))  # True<\/span>\nprint(isinstance(employee, Employee))  # True<\/span>\nprint(isinstance(person, Employee))  # False<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
True<\/span>\nTrue<\/span>\nTrue<\/span>\nFalse<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The output indicates:<\/p>\n\n\n\n