CODEWITHSUNDEEP
pythonpython-3.x
dstodev
dstodev

Reputation: 53

Default Parameters or kwargs?

In Python, there are a few different ways to set default keyword arguments in a function. The ways I know of are:

def default(para_1: str = "this is", para_2: str = "an example"):
    print(para_1, para_2)

and:

def keyword(**kwargs):
    para_1 = kwargs.get("para_1", "this is")
    para_2 = kwargs.get("para_2", "an example")

    print(para_1, para_2)

Both of these functions can be called like so:

default(para_1="this is", para_2="another example")
keyword(para_1="this is", para_2="another example")

to achieve the same effect. The only difference I know of between the two methods are when using mutable default values, where default parameters would need to be written as:

def mutable_default(para_1: dict = None):
    if para_1 is None:
        para_1 = {}

while the kwarg method wouldn't need to be re-structured in the same way, as it is safe with mutable defaults:

def mutable_keyword(**kwargs):
    para_1 = kwargs.get("para_1", {})

Is there a preferred method between the two?

Upvotes: 2

Views: 4888

Answers (1)

kindall
kindall

Reputation: 184230

Yes. Use real arguments as much as possible, because they will be shown in the function's help(). Seeing that a function has a signature (**kwargs) tells you nothing about what arguments it accepts. Seeing the signature (search_term, whole_word=False, case_sensitive=True) is much more valuable.

Using good names is a form of documentation and reduces the need to write other documentation (and the likelihood it will go out of date due to changes in the code).

Upvotes: 8

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