I think it is a common question for every Python programmer including me, “What does ** (double star/asterisk) and * (star/asterisk) do for parameters?”. So in this article, we will discuss this topic.
In the realm of Python programming, the sophistication and adaptability of functions are significantly heightened by the understanding and skillful use of *args and **kwargs. These two idiomatic expressions stand as integral components, providing developers with a nuanced approach to handling a diverse range of function arguments. This formal exploration aims to dissect the mechanics and utility of *args and **kwargs, shedding light on their pivotal roles in Pythonic code.
The Versatility of Positional Arguments
In the introductory act of our exploration, *args takes center stage as a conductor orchestrating a symphony of positional arguments. This idiomatic expression gracefully assembles these arguments into a tuple, creating a dynamic space where functions can seamlessly handle an ever-changing ensemble of inputs.
def foo(*args):
for a in args:
print(a)
With *args, developers compose functions that elegantly dance with any number of positional arguments, transforming their code into a harmonious melody.
Embracing the Ballet of Keyword Arguments
In the elegant ballet of Python functions, **kwargs assumes a leading role, gracefully twirling with an array of keyword arguments. This idiom captures the essence of named parameters, encapsulating them within a dictionary and allowing developers to navigate effortlessly through the keys and values.
def bar(**kwargs):
for key, value in kwargs.items():
print(key, value)
With **kwargs, functions become choreographers, effortlessly navigating through a rich tapestry of keyword arguments.
Harmonizing Fixed and Variable Parameters
The true artistry of function design emerges when *args and **kwargs join hands with regular arguments. This section delves into the magic of creating functions that gracefully dance between the fixed and the variable, accommodating a diverse range of parameters.
def foo(kind, *args, bar=None, **kwargs):
print(kind, args, bar, kwargs)
This symphony of arguments empowers developers to craft functions that adapt seamlessly to the ever-evolving needs of their code.
Showcasing the Unpacking Capabilities
In a moment of pure elegance, *args steps into the spotlight, showcasing its ability to unpack argument lists. This allows for a seamless passage of values, effortlessly transforming a list into individual arguments.
def foo(bar, lee):
print(bar, lee)
With *args, the act of passing multiple values becomes a graceful choreography, simplifying the function call.
Exploring New Roles in Python 3
The grand overture of Python 3 introduces extended roles for *args. Extended Iterable Unpacking and new semantics in function definitions mark significant advancements, adding layers of sophistication to function design.
first, *rest = [1, 2, 3, 4] # The soloist: first = 1, The ensemble: rest = [2, 3, 4]
Orchestrating Python Dicts and Ensuring Order
In the final notes of our exploration, attention is drawn to the orchestration of Python dicts and the newfound orderliness introduced in Python 3.6 onwards. While semantically unordered, this enhancement guarantees the insertion order of keyword arguments, contributing to the predictability of code.