Python functions offer versatile ways to pass arguments. rely on order, while use parameter names. This flexibility allows for clearer, more readable code and easier function calls with multiple parameters.
Default parameter values provide convenience and flexibility in function calls. They allow and can be overridden when needed. Keyword arguments enhance readability, flexibility, and maintainability, making complex function calls more manageable and intuitive.
Function Arguments in Python
Positional vs keyword arguments
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passed to a function based on their position or order
Order of arguments in must match order of parameters in ()
def greet(name, age):
calling
greet("Alice", 25)
assigns
"Alice"
to
name
and
25
to
age
Keyword arguments passed to a function using parameter names along with corresponding values
Order of arguments doesn't matter as long as parameter names are specified
def greet(name, age):
calling
greet(age=25, name="Alice")
achieves same result as
greet("Alice", 25)
Mixing positional and keyword arguments allowed
Positional arguments must come before keyword arguments
greet("Alice", age=25)
is valid, but
greet(name="Alice", 25)
is not
Default parameter values
Specify default value for a parameter in function definition
If argument not provided for that parameter when function is called, default value is used
def greet(name, age=18):
if
age
not provided when calling
greet()
, it defaults to
18
Calling functions with default parameter values
Omit arguments for parameters with (
greet("Alice")
uses default value of
18
for
age
)
Override default values by providing arguments (
greet("Alice", 25)
overrides default
age
with
25
)
Use keyword arguments to specify only parameters you want to override (
greet("Alice", age=25)
overrides default
age
while keeping positional argument for
name
)
Default values create optional parameters in the function definition
Benefits of keyword arguments
Improved readability
Make purpose of each argument clear in function call
draw_rectangle(width=10, height=5)
more readable than
draw_rectangle(10, 5)
Especially useful when function has many parameters or purpose of each argument not immediately clear
Flexibility in argument order
Allow specifying arguments in any order
draw_rectangle(height=5, width=10)
equivalent to
draw_rectangle(width=10, height=5)
Helpful when function has many optional parameters
Selective argument overriding
Override only specific default values
def create_user(name, age=18, email=None):
can call
create_user("Alice", email="alice@example.com")
to override only
email
parameter while keeping default
age
Improved maintainability
If function definition changes to add, remove, or reorder parameters, existing function calls with keyword arguments may not need to be updated
Makes code more maintainable and less prone to errors when refactoring
Function Definition and Calling
Function definition establishes the parameters and their order
Function call involves to match the defined parameters
The relationship between definition and call determines how arguments are interpreted
Key Terms to Review (16)
**kwargs: **kwargs is a special syntax in Python used in function definitions to allow the passing of a variable number of keyword arguments. This enables functions to accept any number of additional arguments without requiring a specific parameter for each one, making code more flexible and easier to manage. When using **kwargs, the additional arguments are captured as a dictionary within the function, where the keys are the argument names and the values are the corresponding values passed in.
Arbitrary Arguments: Arbitrary arguments refer to the ability to pass an unspecified number of arguments to a function in Python. This feature allows for flexibility and dynamic function calls, where the number of arguments can vary based on the specific use case.
Argument Passing: Argument passing refers to the mechanism in programming where data is transferred from one part of a program, such as a function or method, to another. It allows the receiving entity to access and manipulate the passed data as part of its execution.
Default Values: Default values refer to the predetermined values that are assigned to parameters or variables when they are not explicitly provided. These default values serve as fallback options, ensuring that the code can still function even when certain inputs are missing.
Dict(): dict() is a built-in function in Python that creates a new dictionary object. Dictionaries are data structures that store key-value pairs, allowing for efficient storage and retrieval of data.
Dictionary: A dictionary in Python is a collection of key-value pairs where each key is unique. It allows for efficient data retrieval based on the keys.
Dictionary: A dictionary in Python is an unordered collection of key-value pairs, where each key is unique and is associated with a corresponding value. Dictionaries provide a flexible and efficient way to store and retrieve data, making them a fundamental data structure in the language.
Flexible Function Design: Flexible function design refers to the ability to create functions in programming that can adapt to different input parameters and scenarios, allowing for more versatile and reusable code. This concept is particularly important in the context of keyword arguments, which enable functions to accept a variable number of arguments and handle them dynamically.
Function Call: A function call is an expression that executes a named function, passing any required arguments to it. It allows a programmer to invoke a specific piece of code to perform a desired task or operation.
Function Definition: A function definition is the process of creating a named block of code that performs a specific task or operation. It allows programmers to encapsulate and reuse logic, improving code organization and readability.
Keyword Arguments: Keyword arguments are a way of passing arguments to a function in Python where the arguments are identified by the parameter name rather than their position in the function call. This allows for more flexible and readable function calls.
Optional Parameters: Optional parameters are function parameters that are not required to be provided when the function is called. They allow for more flexible and versatile function usage by enabling the caller to decide which parameters to include or exclude based on their specific needs.
Parameter Order: Parameter order refers to the sequence in which arguments are passed to a function or method when it is called. The order of the parameters is crucial, as it determines how the function will interpret and use the provided values.
Positional arguments: Positional arguments are arguments that are passed to a function in a specific order. The position of each argument determines which parameter it corresponds to.
Positional Arguments: Positional arguments refer to the order in which arguments are passed to a function in programming. The position of the arguments determines how they are interpreted and mapped to the corresponding parameters in the function definition.
Unpacking: Unpacking is the process of extracting individual elements from a collection, such as a tuple or a dictionary, and assigning them to separate variables. It allows for efficient and concise handling of data structures in Python.