Uses of arguments and keyword arguments in Python programming
In the realm of Python programming, functions are essential for making code more reusable and easier to understand. One way to increase the adaptability of functions is by using **args and ***kwargs, which allow functions to accept an arbitrary number of positional and keyword arguments, respectively.
**args collects extra positional arguments as a tuple, making it possible for functions to process any number of unnamed arguments. This is particularly useful when the exact number of inputs is uncertain or changes with context. On the other hand, ***kwargs collects extra keyword arguments as a dictionary, enabling functions to handle optional named parameters dynamically, supporting the passing of varied configuration or parameter sets flexibly.
By combining both **args and ***kwargs, functions can accept any mixture of arguments, increasing adaptability without breaking existing code or requiring many overloaded versions. This flexibility is especially valuable when designing reusable libraries, handling data pipelines with variable parameters, or creating base classes whose methods can be overridden with different signatures in subclasses.
Here's an example of a function using both **args and ***kwargs:
```python def example_func(args, *kwargs): print("Positional args:", args) print("Keyword args:", kwargs)
example_func(1, 2, a=3, b=4) ```
This outputs:
showing how the function adapts seamlessly to varying inputs.
The syntax for using **kwargs is straightforward: **kwargs. The use of **kwargs makes it possible to iterate over the arguments using a for loop. Similarly, **args is passed as a tuple and can be iterated over using a for loop.
The main difference between **args and ***kwargs is that **args allows for a variable number of non-keyworded arguments, while ***kwargs allows for a variable number of keyworded arguments.
By rewriting functions to take **args as an argument, they can become more reusable for a variable number of non-keyworded arguments. For instance, the add() function, initially defined to take two arguments, can be rewritten to take **args as an argument, making it more reusable for a variable number of non-keyworded arguments.
In summary, **args and ***kwargs enhance function reusability by making them flexible and extensible, able to handle different numbers and types of inputs without rewriting or overloading. This reduces code duplication and improves interface consistency.
This article was originally published on December 25, 2022, at https://pyshark.com.
References:
- Python documentation: Arguments
- Python documentation: Keyword Arguments
- Real Python: Variable-length Argument Lists
- Real Python: Variable-length Keyword Argument Lists
- Real Python: Variable-length Argument and Keyword Lists
Technology, specifically Python programming, leverages the use of args and kwargs to make functions more adaptable and reusable. args collects extra positional arguments as a tuple, allowing functions to process any number of unnamed arguments, while kwargs collects extra keyword arguments as a dictionary, enabling functions to handle optional named parameters dynamically. This flexibility is beneficial when designing reusable libraries, handling data pipelines with variable parameters, or creating base classes. By rewriting functions to take **args as an argument, they can become more reusable for a variable number of non-keyworded arguments, reducing code duplication and improving interface consistency.
