kimbauters/rusty-exception

Rust-y Exception

This package provides implementations of the Option and Result types in Python, inspired by Rust's Option and Result types. These types offer a safer and more explicit way to handle optional values and error handling compared to using None or raising exceptions directly.

Option

The Option type represents an optional value: either Some (containing a value) or NONE (not containing a value). It provides a way to avoid some of the idiomatic code that can lead to issues, such as using if value: to check for the presence of a value.

Example Usage

from exception import Some, NONE, as_option

@as_option  # trivially convert (existing) code to Option<str>
def get_value(key: str) -> str | None:
    # Some logic to retrieve a value or return None
    ...

result = get_value("key")
if result.is_some():
    value = result.unwrap()
    print(f"Value: {value}")
else:
    print("No value found")

default_value = result.unwrap_or("default")
print(f"Value or default: {default_value}")

Result

The Result type represents either success (Ok) or failure (Err). It provides a way to handle errors and exceptions explicitly, ensuring that they are handled and cannot cause unexpected exceptions to be raised (within the limits of the Python language).

Example Usage

from exception import Ok, Err, as_result

@as_result(ValueError)  # convert code to Result<float, ValueError>
def divide(a: int, b: int) -> float:
    if b == 0:
        raise ValueError("Cannot divide by zero")
    return a / b

result = divide(10, 2)
if result.is_ok():
    value = result.unwrap()
    print(f"Result: {value}")
else:
    error = result.err().unwrap()
    print(f"Error: {error}")

default_value = result.unwrap_or(0)
print(f"Result or default: {default_value}")

# alternatively, to capture *any* exception simply use @as_result()
# to capture many exception types use @as_result(ValueError, TypeError)

Installation

To use the Option and Result types in your Python project, simply copy the exception module into your project directory. Alternatively, install directly from GitHub using pip:

pip install git+https://github.com/kimbauters/rusty-exception.git

The package is not uploaded to PyPi and there are no plans to do so. This package has no requirements, but does rely on modern Python versions (3.10+) and does not do any attempt to support older versions.

Testing

The project includes unit tests for both the Option and Result types. To run the tests, execute the following command:

python -m unittest discover tests

Contributing

Contributions to this project are welcome, as long as you submit pull requests on the project's GitHub repository. This package targets Python 3.10+. All pull requests should fully pass Pylint and Pyright (strict) checks. Any pull request should have full Pytest code coverage (as in sensibly full coverage, not 100% for the sake of it).

License

This project is licensed under the MIT License. Do with it what you want. Don't blame me for anything.