class_singledispatch

A singledispatch() for arguments that are classes annotated as specific types.

Inspired by https://github.com/python/cpython/issues/100623.

A Simple Example

While functools.singledispatch examines the class of the first user argument, class_singledispatch uses the first argument as the class itself and performs the same task with it as functools.singledispatch.

from class_singledispatch import class_singledispatch


class T:
    pass


class OtherT:
    pass


@class_singledispatch
def on_class(cls: type[T], /) -> None:
    print("T!")


@on_class.register
def on_other_class(cls: type[OtherT], /) -> None:
    print("OtherT!")


# Useful for <3.10 without eval_type_backport -- pass the class to the decorator
# not to use the annotation from the function for the targeted class resolution
@on_class.register(SomeOtherT)
def on_some_other_class(cls: type[SomeOtherT], /) -> None:
    print("SomeOtherT!")


on_class(T)  # T!
on_class(OtherT)  #  OtherT!
on_class(SomeOtherT)  #  SomeOtherT!

Installation

You might simply install it with pip:

pip install class-singledispatch

[!Note] class-singledispatch supports modern type hinting.
To use PEP 585 or PEP 604 annotations on Python <3.10, install class-singledispatch[modern-type-hints].

If you use Poetry, then you might want to run:

poetry add class-singledispatch

For Contributors

[!Note] If you use Windows, it is highly recommended to complete the installation in the way presented below through WSL2.

1. Fork the class_singledispatch repository on GitHub.

2. Install Poetry.
   Poetry is an amazing tool for managing dependencies & virtual environments, building packages and publishing them. You might use pipx to install it globally (recommended):

   pipx install poetry
   

   _{If you encounter any problems, refer to the official documentation for the most up-to-date installation instructions.}

   Be sure to have Python 3.8 installed—if you use pyenv, simply run:

   pyenv install 3.8
   

3. Clone your fork locally and install dependencies.

   git clone https://github.com/your-username/class_singledispatch path/to/class_singledispatch
   cd path/to/class_singledispatch
   poetry env use $(cat .python-version)
   poetry install
   

   Next up, simply activate the virtual environment and install pre-commit hooks:

   poetry shell
   pre-commit install
   

For more information on how to contribute, check out CONTRIBUTING.md.
Always happy to accept contributions! ❤️

Legal Info

© Copyright by Bartosz Sławecki (@bswck).
This software is licensed under the terms of MIT License.