When should I use default arguments in Python?

When should I use default arguments in Python?

Default arguments in Python are useful when you want to provide a default value for a parameter, making it optional.

Can you give me an example of a function with default arguments?

Sure! Here's a simple example:

def greet(name, greeting='Hello'):
    return f'{greeting}, {name}!'

In this case, if you call greet('Alice'), it will return 'Hello, Alice!'. If you call greet('Alice', 'Hi'), it will return 'Hi, Alice!'.

Are there any downsides to using default arguments?

Yes, one downside is that if you use mutable default arguments like lists or dictionaries, they can retain changes across function calls, which can lead to unexpected behavior.

How can I avoid issues with mutable default arguments?

To avoid issues, use None as a default value and then initialize the mutable object inside the function:

def append_to_list(item, my_list=None):
    if my_list is None:
        my_list = []
    my_list.append(item)
    return my_list