close

How do I add default parameters to functions when using type hinting?

Hello Guys, How are you all? Hope You all Are Fine. Today We Are Going To learn about How do I add default parameters to functions when using type hinting in Python. So Here I am Explain to you all the possible Methods here.

Without wasting your time, Let’s start This Article.

Table of Contents

How do I add default parameters to functions when using type hinting?

  1. How do I add default parameters to functions when using type hinting?

    If you're using typing (introduced in Python 3.5) you can use typing.Optional, where Optional[X] is equivalent to Union[X, None]. It is used to signal that the explicit value of None is allowed.

  2. add default parameters to functions when using type hinting

    If you're using typing (introduced in Python 3.5) you can use typing.Optional, where Optional[X] is equivalent to Union[X, None]. It is used to signal that the explicit value of None is allowed.

Method 1

Your second way is correct.

def foo(opts: dict = {}):
    pass

print(foo.__annotations__)

this outputs

{'opts': <class 'dict'>}

It’s true that’s it’s not listed in PEP 484, but type hints are an application of function annotations, which are documented in PEP 3107. The syntax section makes it clear that keyword arguments works with function annotations in this way.

I strongly advise against using mutable keyword arguments.

Method 2

If you’re using typing (introduced in Python 3.5) you can use typing.Optional, where Optional[X] is equivalent to Union[X, None]. It is used to signal that the explicit value of None is allowed. From typing.Optional:

def foo(arg: Optional[int] = None) -> None:
    ...

Summery

It’s all About this issue. Hope all Methods helped you a lot. Comment below Your thoughts and your queries. Also, Comment below which Method worked for you? Thank You.

Also, Read