{"id":2549,"date":"2021-10-16T09:32:03","date_gmt":"2021-10-16T09:32:03","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=2549"},"modified":"2025-03-31T07:54:51","modified_gmt":"2025-03-31T07:54:51","slug":"python-methods","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-oop\/python-methods\/","title":{"rendered":"Python Methods"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about Python methods and the differences between functions and methods.<\/p>\n\n\n\n

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

By definition, a method is a function<\/a> that is bound to an instance of a class<\/a>. This tutorial helps you understand how it works under the hood.<\/p>\n\n\n\n

The following defines a Request<\/code> class that contains a function send()<\/code>:<\/p>\n\n\n

class<\/span> Request<\/span>:<\/span>\n    def<\/span> send<\/span>()<\/span>:<\/span>\n        print('Sent'<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
And you can call the send()<\/code> function via the Request<\/code> class like this:<\/p>\n\n\n
Request.send() # Sent<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The send()<\/code> is a function object, which is an instance of the function<\/code> class as shown in the following output:<\/p>\n\n\n
print(Request.send)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
<function Request.send at 0x00000276F9E00310<\/span>><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The type of the send<\/code> is function<\/code>:<\/p>\n\n\n
print(type(Request.send))<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
<class<\/span> 'function<\/span>'><\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following creates a new instance of the Request<\/code> class:<\/p>\n\n\n
http_request = Request()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
If you display the http_request.send<\/code>, it’ll return a bound method object:<\/p>\n\n\n
print(http_request.send)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
<bound method Request.send of <__main__.Request object at 0x00000104B6C3D580<\/span>>><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
So the http_request.send<\/code> is not a function like Request.send<\/code>. The following checks if the Request.send<\/code> is the same object as http_request.send<\/code>. It’ll returns False<\/code> as expected:<\/p>\n\n\n
print(type(Request.send) is<\/span> type(http_request.send))<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The reason is that the type of the Request.send<\/code> is function<\/code> while the type of the http_request.send<\/code> is method<\/code>, as shown below:<\/p>\n\n\n
print(type(http_request.send))  # <class 'method'><\/span>\nprint(type(Request.send))  # <class 'function'><\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
So when you define a function inside a class, it’s purely a function. However, when you access that function via an object, the function becomes a method. <\/p>\n\n\n\n
Therefore, a method is a function that is bound to an instance of a class.<\/p>\n\n\n\n
If you call the send()<\/code> function via the http_request<\/code> object, you’ll get a TypeError<\/code> as follows:<\/p>\n\n\n
http_request.send()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Error:<\/p>\n\n\n
TypeError: send() takes 0<\/span> positional arguments but 1<\/span> was given<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Because the http_request.send<\/code> is a method that is bound to the http_request<\/code> object, Python always implicitly passes the object to the method as the first argument.<\/p>\n\n\n\n
The following redefines the Request<\/code> class where the send<\/code> function accepts a list of arguments:<\/p>\n\n\n
class<\/span> Request<\/span>:<\/span>\n    def<\/span> send<\/span>(*args)<\/span>:<\/span>\n        print('Sent'<\/span>, args)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following calls the send<\/code> function from the Request<\/code> class:<\/p>\n\n\n
Request.send()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Sent ()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The send()<\/code> function doesn’t receive any arguments.<\/p>\n\n\n\n
However, if you call the send()<\/code> function from an instance of the Request<\/code> class, the args<\/code> is not empty:<\/p>\n\n\n
http_request.send()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Sent (<__main__.Request object at 0x000001374AF4D580<\/span>>,)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this case, the send()<\/code> method receives an object which is the http_request<\/code>, which is the object that it is bound to.<\/p>\n\n\n\n
The following illustrates that the object that calls the send()<\/code> method is the one that Python implicitly passes into the method as the first argument:<\/p>\n\n\n
print(hex(id(http_request)))\nhttp_request.send()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
0x1ee3a74d580<\/span>\nSent (<__main__.Request object at 0x000001EE3A74D580<\/span>>,)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The http_request<\/code> object is the same as the one Python passes to the send()<\/code> method as the first argument because they have the same memory address. In other words, you can access the instance of the class as the first argument inside the send()<\/code> method:<\/p>\n\n\n\n
The following method call:<\/p>\n\n\n
http_request.send()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
is equivalent to the following function call:<\/p>\n\n\n
Request.send(http_request)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
For this reason, a method of an object always has the object as the first argument. By convention, it is called self<\/code>:<\/p>\n\n\n
class<\/span> Request<\/span>:<\/span>\n    def<\/span> send<\/span>(self)<\/span>:<\/span>\n        print('Sent'<\/span>, self)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
If you have worked with other programming languages such as Java or C#, the self<\/code> is the same as the this<\/code> object.<\/p>\n\n\n\n
Summary #<\/a><\/h2>\n\n\n\n