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Python can't use ** outside of function definition

Disclaimer: I am new to Python.

If you read this article, it lists ** as being able to unpack dictionaries. I was trying this out.

  1. my_dict = {"key1": 1, "key2": {"inner_key": 3} }
  2. unpacked_dict = **my_dict

Returns: SyntaxError: invalid syntax

What am I missing? I know ** is used mainly with **kwargs, is my problem that ** can only be used in a function definition?

Solution

  • You can use it to unpack it into other dictionaries. It doesn't work in the way I assume you are trying to do it which is taken inner dictionaries from values and make them all part of the same level. From the article you referenced:

    For example we can copy a dictionary while adding a new value to it:

    >>> date_info = {'year': '2020', 'month': '01', 'day': '7'}
>>> event_info = {**date_info, 'group': "Python Meetup"}
>>> event_info
{'year': '2020', 'month': '01', 'day': '7', 'group': 'Python Meetup'}

    Or copy/merge dictionaries while overriding particular values:

    >>> event_info = {'year': '2020', 'month': '01', 'day': '7', 'group': 'Python Meetup'}
>>> new_info = {**event_info, 'day': "14"}
>>> new_info
{'year': '2020', 'month': '01', 'day': '14', 'group': 'Python Meetup'}

    This was added as of Python 3.5+, more info is in PEP 448.