{"id":139,"date":"2024-01-25T13:37:09","date_gmt":"2024-01-25T13:37:09","guid":{"rendered":"https:\/\/learnpython.elegantwallp.com\/?p=139"},"modified":"2024-01-25T13:37:11","modified_gmt":"2024-01-25T13:37:11","slug":"python-methods","status":"publish","type":"post","link":"https:\/\/learnpython.elegantwallp.com\/2024\/01\/25\/python-methods\/","title":{"rendered":"Python Methods"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you\u2019ll learn about Python methods and the differences between functions and methods.<\/p>\n\n\n\n

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

By definition, a method is a\u00a0function\u00a0that is bound to an instance of a\u00a0class. This tutorial helps you understand how it works under the hood.<\/p>\n\n\n\n

The following defines a\u00a0Request<\/code>\u00a0class that contains a function\u00a0send()<\/code>:<\/p>\n\n\n\n

class Request: def send(): print('Sent')<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
And you can call the\u00a0send()<\/code>\u00a0function via the\u00a0Request<\/code>\u00a0class like this:<\/p>\n\n\n\n
Request.send() # Sent<\/em><\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The\u00a0send()<\/code>\u00a0is a function object, which is an instance of the\u00a0function<\/code>\u00a0class as shown in the following output:<\/p>\n\n\n\n
print(Request.send)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
<function Request.send at 0x00000276F9E00310><\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The type of the\u00a0send<\/code>\u00a0is\u00a0function<\/code>:<\/p>\n\n\n\n
print(type(Request.send))<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
<class 'function'><\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The following creates a new instance of the\u00a0Request<\/code>\u00a0class:<\/p>\n\n\n\n
http_request = Request()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
If you display the\u00a0http_request.send<\/code>, it\u2019ll return a bound method object:<\/p>\n\n\n\n
print(http_request.send)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
<bound method Request.send of <__main__.Request object at 0x00000104B6C3D580>><\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
So the\u00a0http_request.send<\/code>\u00a0is not a function like\u00a0Request.send<\/code>. The following checks if the\u00a0Request.send<\/code>\u00a0is the same object as\u00a0http_request.send<\/code>. It\u2019ll returns\u00a0False<\/code>\u00a0as expected:<\/p>\n\n\n\n
print(type(Request.send) is type(http_request.send))<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The reason is that the type of the\u00a0Request.send<\/code>\u00a0is\u00a0function<\/code>\u00a0while the type of the\u00a0http_request.send<\/code>\u00a0is\u00a0method<\/code>, as shown below:<\/p>\n\n\n\n
print(type(http_request.send)) # <class 'method'><\/em> print(type(Request.send)) # <class 'function'><\/em><\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
So when you define a function inside a class, it\u2019s 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\u00a0send()<\/code>\u00a0function via the\u00a0http_request<\/code>\u00a0object, you\u2019ll get a\u00a0TypeError<\/code>\u00a0as follows:<\/p>\n\n\n\n
http_request.send()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Error:<\/p>\n\n\n\n
TypeError: send() takes 0 positional arguments but 1 was given<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\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\u00a0Request<\/code>\u00a0class where the\u00a0send<\/code>\u00a0function accepts a list of arguments:<\/p>\n\n\n\n
class Request: def send(*args): print('Sent', args)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The following calls the\u00a0send<\/code>\u00a0function from the\u00a0Request<\/code>\u00a0class:<\/p>\n\n\n\n
Request.send()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
Sent ()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
The send()<\/code> function doesn\u2019t receive any arguments.<\/p>\n\n\n\n
However, if you call the\u00a0send()<\/code>\u00a0function from an instance of the\u00a0Request<\/code>\u00a0class, the\u00a0args<\/code>\u00a0is not empty:<\/p>\n\n\n\n
http_request.send()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
Sent (<__main__.Request object at 0x000001374AF4D580>,)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\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\u00a0send()<\/code>\u00a0method is the one that Python implicitly passes into the method as the first argument:<\/p>\n\n\n\n
print(hex(id(http_request))) http_request.send()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
Output:<\/p>\n\n\n\n
0x1ee3a74d580 Sent (<__main__.Request object at 0x000001EE3A74D580>,)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\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\n
http_request.send()<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
is equivalent to the following function call:<\/p>\n\n\n\n
Request.send(http_request)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\n\n\n
For this reason, a method of an object always has the object as the first argument. By convention, it is called\u00a0self<\/code>:<\/p>\n\n\n\n
class Request: def send(self): print('Sent', self)<\/code>Code language: Python (python)<\/small><\/code><\/pre>\n\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","protected":false},"excerpt":{"rendered":"
Summary: in this tutorial, you\u2019ll learn about Python methods and the differences between functions and methods. Introduction to the Python methods By definition, a method is a\u00a0function\u00a0that is bound to an instance of a\u00a0class. This tutorial helps you understand how it works under the hood. The following defines a\u00a0Request\u00a0class that contains a function\u00a0send(): And you […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[25],"tags":[],"class_list":["post-139","post","type-post","status-publish","format-standard","hentry","category-1-classes-and-objects"],"_links":{"self":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts\/139","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/comments?post=139"}],"version-history":[{"count":1,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts\/139\/revisions"}],"predecessor-version":[{"id":140,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/posts\/139\/revisions\/140"}],"wp:attachment":[{"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/media?parent=139"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/categories?post=139"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/learnpython.elegantwallp.com\/wp-json\/wp\/v2\/tags?post=139"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}