Arbitrary Arguments (*args)

In Python, the *args syntax is used to pass a varying number of arguments to a function. The *args parameter allows you to pass any number of positional arguments to a function, and it collects them into a tuple.

Let's implement the multiply() function that can accept a variable number of arguments:


              1234
            
def multiply(*args):
    print(args, type(args))

multiply(12, 11, 52, 33)

The function multiply() accepts a variable number of arguments using the syntax *args. The arguments are then stored in a tuple called args. We can use a loop to multiply all the arguments together, as shown below:


              1234567891011
            
def multiply(*args):
    result = 1
    
    for arg in args:
        print(result, "*", arg)
        result *= arg
    
    return result

print("Result =", multiply(12, 11, 52, 33))
print("Result without args:", multiply())

Now, you can see that our function works with no arguments as well as with many arguments.

Note
The parameter *args is commonly referred to as variable-length argument or arbitrary argument list.

If we need a function that should take from one/two/... to many arguments, a combination of positional arguments and arbitrary arguments, such as *args.


              12345678
            
def multiply(first, second, *args):
    result = first * second
    for arg in args:
        result *= arg
    return result

print("Correct:", multiply(5, 2, 5, 1, 3))
print("Not correct", multiply(1))

In the example above, you can see that our function returned 150 when called with 2 or more arguments and raised a TypeError when called with fewer than 2 arguments.

It is important to note that the positional arguments should be defined before the optional arguments:


              123456789
            
def multiply(first, second, *args):
    print("first =", first)
    print("second =", second)
    result = first * second
    for arg in args:
        result *= arg
    return result

print("Result:", multiply(11, 22, first=33, second=44, 55))

Tudo estava claro?

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Seção 2. Capítulo 3