{"id":511,"date":"2020-10-13T09:09:47","date_gmt":"2020-10-13T09:09:47","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=511"},"modified":"2025-03-31T04:31:49","modified_gmt":"2025-03-31T04:31:49","slug":"python-kwargs","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-kwargs\/","title":{"rendered":"Python **kwargs"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about the Python **kwargs<\/code> parameters.<\/p>\n\n\n\n

Introduction to the Python **kwargs parameters #<\/a><\/h2>\n\n\n\n

In Python, a function<\/a> can have a parameter preceded by two stars (**). For example: **kwwargs<\/code><\/p>\n\n\n\n

The **kwargs<\/code> is called a keyword parameter. <\/p>\n\n\n\n

When a function has the **kwargs<\/code> parameter, it can accept a variable number of keyword arguments<\/a> as a dictionary<\/a>.<\/p>\n\n\n\n

The two stars (**<\/code>) are important. However, the name kwargs<\/code> is by convention. Therefore, you can use any other meaningful names such as **configs<\/code> and **files<\/code>.<\/p>\n\n\n\n

The following example defines a function called connect()<\/code> that accepts a **kwargs<\/code> parameter:<\/p>\n\n\n

def<\/span> connect<\/span>(**kwargs)<\/span>:<\/span>\n    print(type(kwargs))\n    print(kwargs)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
The following function call shows an empty dictionary to the screen:<\/p>\n\n\n
def<\/span> connect<\/span>(**kwargs)<\/span>:<\/span>\n    print(type(kwargs))\n    print(kwargs)\n\nconnect()<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
<class<\/span> 'dict<\/span>'>\n{}<\/span><\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, we didn’t pass any arguments to the connect()<\/code> function, the kwargs<\/code> is empty dictionary.<\/p>\n\n\n\n
The following calls the connect()<\/code> function and passes some keyword arguments into it:<\/p>\n\n\n
def<\/span> connect<\/span>(**kwargs)<\/span>:<\/span>\n    print(type(kwargs))\n    print(kwargs)\n\nconnect(server='localhost'<\/span>, port=3306<\/span>, user='root'<\/span>, password='Py1hon!Xt'<\/span>)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
It shows the following dictionary to the screen:<\/p>\n\n\n
<class<\/span> 'dict<\/span>'>\n{'server<\/span>':<\/span> 'localhost'<\/span>, 'port'<\/span>: 3306<\/span>, 'user'<\/span>: 'root'<\/span>, 'password'<\/span>: 'Py1hon!Xt'<\/span>}<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Inside the connect()<\/code> function, you can use the kwargs<\/code> argument as a dictionary.<\/p>\n\n\n\n
If you want to pass a dictionary to the function, you need to add two stars (**<\/code>) to the argument like this:<\/p>\n\n\n
def<\/span> connect<\/span>(**kwargs)<\/span>:<\/span>\n    print(kwargs)\n\n\nconfig = {'server'<\/span>: 'localhost'<\/span>,\n        'port'<\/span>: 3306<\/span>,\n        'user'<\/span>: 'root'<\/span>,\n        'password'<\/span>: 'Py1thon!Xt12'<\/span>}\n\nconnect(**config)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
If a function has the **kwargs<\/code> parameter and other parameters, you need to place the **kwargs<\/code> after other parameters. Otherwise, you’ll get an error.<\/p>\n\n\n\n
The syntax of the following connect()<\/code> function is correct:<\/p>\n\n\n
def<\/span> connect<\/span>(fn, **kwargs)<\/span>:<\/span>\n    print(kwargs)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
However, the syntax of this function causes a SyntaxError<\/code>:<\/p>\n\n\n
def<\/span> connect<\/span>(**kwargs, fn)<\/span>:<\/span>\n    print(kwargs)<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Using both *args and **kwargs arguments #<\/a><\/h2>\n\n\n\n
The following function has both *args<\/code> and **kwargs<\/code> parameters:<\/p>\n\n\n
def fn(*args, **kwargs):\n    print<\/span>(args)\n    print<\/span>(kwargs)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The fn<\/code> function can accept a variable number of the positional arguments. Python will pack them as a tuple and assign the tuple to the args<\/code> argument.<\/p>\n\n\n\n
The fn<\/code> function also accepts a variable number of keyword arguments. Python will pack them as a dictionary and assign the dictionary to the kwargs<\/code> argument.<\/p>\n\n\n\n
For example:<\/p>\n\n\n
def fn(*args, **kwargs):\n    print<\/span>(args)\n    print<\/span>(kwargs)\n\nfn(1<\/span>, 2<\/span>, x=10<\/span>, y=20<\/span>)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
(1<\/span>, 2<\/span>)\n{'x'<\/span>: 10<\/span>, 'y'<\/span>: 20<\/span>}<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n