Python typing signature (typing.Callable) for function with kwargs

Python typing signature (typing.Callable) for function with kwargs

When defining the type signature for a Python function that accepts keyword arguments (kwargs), you can use the typing.Callable type along with the ** syntax to indicate the keyword arguments. Here's how you can do it:

from typing import Callable def function_with_kwargs(arg1: int, arg2: str, callback: Callable[..., None], **kwargs: int) -> None: # Your function implementation result = arg1 + arg2 callback(result, **kwargs)

In this example, callback is a parameter of type Callable[..., None], which means it's a callable that takes any number of arguments (including keyword arguments) and returns None. The **kwargs parameter allows you to pass any additional keyword arguments to the callback function.

When you call callback(result, **kwargs), the keyword arguments will be unpacked and passed to the callback function.

Here's how you can use this function:

def my_callback(result: str, **extra_kwargs: int) -> None: print("Result:", result) print("Extra kwargs:", extra_kwargs) function_with_kwargs(42, "Hello", my_callback, a=1, b=2, c=3)

In this example, the function_with_kwargs function takes the arguments arg1 and arg2, a callback function my_callback, and any number of additional keyword arguments. The my_callback function receives the result argument and any additional keyword arguments passed to function_with_kwargs.

Remember to adjust the types and argument names according to your specific use case.

Examples

  1. "Python: How to define a Callable with arbitrary kwargs?"

    • This query explores how to use typing.Callable with a flexible signature to accept arbitrary keyword arguments.
    from typing import Callable, Any def process_with_kwargs(func: Callable[..., Any], **kwargs): # Calling a function with arbitrary keyword arguments return func(**kwargs) def example_function(x: int, y: int, z: int = 0): return x + y + z # Usage with the function and keyword arguments result = process_with_kwargs(example_function, x=1, y=2, z=3) # Outputs: 6

  2. "Python: How to specify a Callable with specific kwargs keys?"

    • This query discusses type hinting when the kwargs should have specific keys.
    from typing import Callable def call_with_specific_kwargs(func: Callable[[int, int], int], **kwargs): # Expecting `x` and `y` keyword arguments return func(kwargs["x"], kwargs["y"]) def add(x: int, y: int): return x + y # Using with keyword arguments result = call_with_specific_kwargs(add, x=10, y=20) # Outputs: 30

  3. "Python: Typing a Callable that returns different results based on kwargs"

    • This query demonstrates a Callable with a flexible return type depending on keyword arguments.
    from typing import Callable, Union def flexible_return(func: Callable[..., Union[int, str]], **kwargs): return func(**kwargs) def get_value(a: int, as_str: bool = False): return str(a) if as_str else a # Example of return type depending on `kwargs` result1 = flexible_return(get_value, a=42, as_str=True) # Outputs: '42' result2 = flexible_return(get_value, a=42, as_str=False) # Outputs: 42

  4. "Python: How to type hint a function with default kwargs values?"

    • This query explores a Callable with type hints for functions with default keyword arguments.
    from typing import Callable, Dict def default_kwargs(func: Callable[..., int], **kwargs): # Provide default keyword arguments defaults = {"x": 1, "y": 2} defaults.update(kwargs) return func(defaults["x"], defaults["y"]) def add(x: int, y: int): return x + y # Call with or without `kwargs` result1 = default_kwargs(add) # Outputs: 3 (using defaults) result2 = default_kwargs(add, x=10) # Outputs: 12 (override `x`)

  5. "Python: Type hinting for a Callable with a specified return type"

    • This query demonstrates type hinting for a Callable with specific kwargs and return type.
    from typing import Callable def call_with_return_type(func: Callable[[int, int], int], **kwargs): return func(kwargs["x"], kwargs["y"]) def multiply(x: int, y: int): return x * y # Specifying return type with specific `kwargs` result = call_with_return_type(multiply, x=3, y=4) # Outputs: 12

  6. "Python: Handling a Callable that has kwargs in decorator functions"

    • This query explores how to use kwargs with type-hinted decorators.
    from typing import Callable, Any def add_kwargs_decorator(decorator: Callable[..., Any]): # Decorate a function, allowing `kwargs` def wrapper(func: Callable[..., Any], **kwargs): return decorator(func, **kwargs) return wrapper def log_call(func: Callable[..., Any], **kwargs): print(f"Calling function: {func.__name__} with {kwargs}") return func(**kwargs) decorated = add_kwargs_decorator(log_call) # Decorated function using `kwargs` def say_hello(name: str): return f"Hello, {name}!" print(decorated(say_hello, name="Alice")) # Outputs: "Hello, Alice!"

  7. "Python: Type hinting Callable that changes behavior based on kwargs"

    • This query demonstrates a function with conditional behavior depending on kwargs.
    from typing import Callable, Any def conditional_call(func: Callable[..., Any], **kwargs): # Conditional behavior based on `kwargs` if kwargs.get("reverse"): return func(kwargs["y"], kwargs["x"]) # Swap `x` and `y` else: return func(kwargs["x"], kwargs["y"]) def subtract(x: int, y: int): return x - y # Conditional execution using `kwargs` result1 = conditional_call(subtract, x=10, y=5) # Outputs: 5 result2 = conditional_call(subtract, x=10, y=5, reverse=True) # Outputs: -5

  8. "Python: Type hinting for Callable with varying numbers of kwargs"

    • This query explores using **kwargs when the number of keyword arguments is unknown.
    from typing import Callable, Any def flexible_call(func: Callable[..., Any], **kwargs): # Accept varying numbers of keyword arguments return func(**kwargs) def concatenate_strings(**kwargs): return " ".join(kwargs.values()) # Accepting varying `kwargs` result1 = flexible_call(concatenate_strings, first="Hello", second="world") # Outputs: "Hello world" result2 = flexible_call(concatenate_strings, one="Python", two="is", three="awesome") # Outputs: "Python is awesome"

  9. "Python: Using typing.Protocol to specify Callable with kwargs"

    • This query demonstrates how to use Protocol to define an interface for Callable with kwargs.
    from typing import Protocol, Any class HasKwargs(Protocol): def __call__(self, **kwargs: Any) -> Any: ... def execute_with_protocol(func: HasKwargs, **kwargs): return func(**kwargs) def greet(**kwargs): return f"Hello, {kwargs.get('name', 'there')}!" # Protocol-based type hinting with `kwargs` result = execute_with_protocol(greet, name="Bob") # Outputs: "Hello, Bob!"

  10. "Python: Handling Callable with nested kwargs structures"

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