Python - Keyword Arguments

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Keyword Arguments

Python allows to pass function arguments in the form of keywords which are also called named arguments. Variables in the function definition are used as keywords. When the function is called, you can explicitly mention the name and its value.

Example of Keyword Arguments

# Function definition is here
def printinfo( name, age ):
   "This prints a passed info into this function"
   print ("Name: ", name)
   print ("Age ", age)
   return

# Now you can call printinfo function
# by positional arguments
printinfo ("Naveen", 29)

# by keyword arguments
printinfo(name="miki", age = 30)

By default, the function assigns the values to arguments in the order of appearance. In the second function call, we have assigned the value to a specific argument

It will produce the following output −

Name: Naveen
Age 29
Name: miki
Age 30

Let us try to understand more about keyword argument with the help of following function definition −

def division(num, den):
   quotient = num/den
   print ("num:{} den:{} quotient:{}".format(num, den, quotient))

division(10,5)
division(5,10)

Since the values are assigned as per the position, the output is as follows −

num:10 den:5 quotient:2.0
num:5 den:10 quotient:0.5

Calling Function With Keyword Arguments

Instead of passing the values with positional arguments, let us call the function with keyword arguments −

Example

division(num=10, den=5)
division(den=5, num=10)

It will produce the following output −

num:10 den:5 quotient:2.0
num:10 den:5 quotient:2.0

Order of Keyword Arguments

When using keyword arguments, it is not necessary to follow the order of formal arguments in function definition.

Using keyword arguments is optional. You can use mixed calling. You can pass values to some arguments without keywords, and for others with keyword.

division(10, den=5)

However, the positional arguments must be before the keyword arguments while using mixed calling.

Try to call the division() function with the following statement.

def division(num, den):
   quotient = num/den
   print ("num:{} den:{} quotient:{}".format(num, den, quotient))

division(num=5, 10)

As the Positional argument cannot appear after keyword arguments, Python raises the following error message −

    division(num=5, 10)
                      ^
SyntaxError: non-keyword arg after keyword arg