Definition
The **kwargs syntax in Python is used in a function definition to accept an arbitrary number of keyword arguments, which are collected into a dictionary.
Why It Matters
Using **kwargs allows functions to accept optional, named arguments dynamically, which is essential for writing extensible APIs, decorators, and wrapper functions.
Core Concepts
- Syntax: The double asterisk (
**) is the actual operator that performs the key-value packing/unpacking; the namekwargsis a strong community convention.
def build_profile(first, last, **user_info):
profile = {'first_name': first, 'last_name': last}
for key, value in user_info.items():
profile[key] = value
return profile
user_profile = build_profile('albert', 'einstein', location='princeton', field='physics')
print(user_profile)- Data Type: Inside the function, the parameter prefixed with
**is treated as a dictionary. - Unpacking: The double asterisk can also be used in function calls to unpack an existing dictionary into named keyword arguments.