Variable-length arguments in Python

You may need to process a function for more arguments than you specified while defining the function. These arguments are called variable-length arguments and are not named in the function definition, unlike required and default arguments.

Syntax

Syntax for a function with non-keyword variable arguments is this −

def functionname([formal_args,] *var_args_tuple):
    "function_docstring"
    function_suite
    return [expression]

An asterisk (*) is placed before the variable name that holds the values of all nonkeyword variable arguments. This tuple remains empty if no additional arguments are specified during the function call.

Using *args for Variable Arguments

The following example demonstrates how to accept variable number of arguments using *args ?

# Function definition with variable arguments
def printinfo(arg1, *vartuple):
    """This prints a variable passed arguments"""
    print("Output is:")
    print(arg1)
    for var in vartuple:
        print(var)

# Now you can call printinfo function
printinfo(10)
print()  # Add spacing between calls
printinfo(70, 60, 50)

Output is:
10

Output is:
70
60
50

Using **kwargs for Keyword Arguments

Python also supports variable-length keyword arguments using double asterisks (**kwargs) ?

def print_details(name, **kwargs):
    """Print name and additional details"""
    print(f"Name: {name}")
    for key, value in kwargs.items():
        print(f"{key}: {value}")

# Call with keyword arguments
print_details("John", age=25, city="New York", job="Engineer")

Name: John
age: 25
city: New York
job: Engineer

Combining Both *args and **kwargs

You can use both *args and **kwargs in the same function definition ?

def flexible_function(required_arg, *args, **kwargs):
    """Function that accepts all types of arguments"""
    print(f"Required argument: {required_arg}")
    
    if args:
        print("Additional positional arguments:")
        for arg in args:
            print(f"  {arg}")
    
    if kwargs:
        print("Keyword arguments:")
        for key, value in kwargs.items():
            print(f"  {key}: {value}")

# Test the function
flexible_function("Hello", 1, 2, 3, name="Alice", age=30)

Required argument: Hello
Additional positional arguments:
  1
  2
  3
Keyword arguments:
  name: Alice
  age: 30

Comparison

Conclusion

Variable-length arguments provide flexibility in function definitions. Use *args for variable positional arguments and **kwargs for variable keyword arguments to create more versatile functions.