Overloadlib¶

Features¶

Introduces @overload, @override and @<Function>.add decorators, allowing one to overload and override functions. Functions are then called according to their argument types:

@overload
def func(var: str):
   return var

# via @<Function>.add
@func.add
def _(var: int) -> str:
   return str(var * 5)

# via @overload
@overload
def func() -> str:
   return "Functions don't need to have arguments."

# via @override
@override(funcs=[func])
def new(str_1: str, int_1: int):
   return str_1 * int_1

assert func("a") == "a" == new("a")
assert func(1) == "5" == new(1)
assert func() == "Functions don't need to have arguments." == new()
assert new("house", 2) == "househouse"

Raises human readable errors, if no callable was determined with the given arguments. For example the following given:

@overload
def some_func(str_1: str, int_1: int):
   return str_1 + str(int_1)

@overload
def some_func(str_1: str):
   return str_1

Calling:

>>> some_func(str_1=2)
PyOverloadError:
Error when calling:
(__main__.some_func):
        def some_func(str_1: int):
                ...:
        'str_1' needs to be of type (<class 'str'>,) (is type <class 'int'>)

or

>>> some_func(10)
__main__.NoFunctionFoundError: No matching function found.
Following definitions of 'some_func' were found:
(__main__.some_func):
        def some_func(str_1: str, int_1: int):
                ...
(__main__.some_func):
        def some_func(str_1: str):
                ...
The following call was made:
(__main__.some_func):
        def some_func(int_1: int):
                ...

Any type of variables is allowed: Build-in ones like str, int, List but also own ones, like classes etc.
@overload uses get_type_hints to identify the right function call via type-checking. Hence, it may also be used as a type-checker for functions.
Forgot, which overloads of a specific function have been implemented? No worries, you can print them with their typing information using print(func_versions_info(<my_func>)), e.g.

>>> print(func_versions_info(some_func))

Following overloads of 'some_func' exist:
(__main__.some_func):
         def some_func(str_1: str, int_1: int):
               ...
(__main__.some_func):
         def some_func(str_1: str):
               ...

Requirements¶

Requires Python 3.7+.

Installation¶

You can install Overloadlib via pip from PyPI:

$ pip install overloadlib

or install with Poetry

$ poetry add overloadlib

Then you can run

$ overloadlib --help

or with Poetry:

$ poetry run overloadlib --help

<details> <summary>Installing Poetry</summary> <p>

To download and install Poetry run (with curl):

$ curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/install-poetry.py | python -

or on windows (without curl):

$ (Invoke-WebRequest -Uri https://raw.githubusercontent.com/python-poetry/poetry/master/install-poetry.py -UseBasicParsing).Content | python -

</p> </details>

Uninstall¶

If you wan to uninstall the package, simply run

$ pip uninstall overloadlib

or with Poetry:

$ poetry remove overloadlib

Usage¶

Please see the Command-line Reference for details.

Contributing¶

Contributions are very welcome. To learn more, see the Contributor Guide.

License¶

Distributed under the terms of the MIT license, Overloadlib is free and open source software.

Issues¶

If you encounter any problems, please file an issue along with a detailed description.

Credits¶

This project was generated by a template inspired by @cjolowicz’s Hypermodern Python Cookiecutter template and @TezRomacH’s python-package-template

Usage¶

Import

Imports need to come form overloadlib.overloadlib. Importing via

from overloadlib.overloadlib import *

imports overload and override decorators, as well as func_versions_info.

Overloading of functions can be done via the @overload or @override decorator.

@overload¶

Overloading of functions:

@overload
def func(var: str):
    return var

@overload
def func(var: int):
    return str(var * 5)

func("a") == "a"  # True
"a: " + func(1)  # "a: 5"

Overloading of methods (or mixtures of both) are also possible using the same decorator:

@dataclass
class Hello:
    text: str = "Hello"

class Some:
    def __init__(self) -> None:
        pass

    @overload
    def func(self, str_1: str, int_1: int) -> str:
        return str_1 + str(int_1)

    @overload
    def func(self, str_1: str) -> str:
        return str_1

    @overload
    def func(self, obj: Hello) -> str:
        return obj.text

@overload
def func(str_1: str) -> str:
    return "yummy " + str_1

Note that own classes, can be given as types to the function. Furthermore, methods and functions ma have the same name. Possible calls could now look like this:

# Giving only *args
some.func("Number: ", 1)  # "Number: 1"

# Giving **kwargs
some.func(str_1="Number: ", int_1=1)  # "Number: 1"

# An object as argument
some.func(Hello())  # "Hello"

# Calling the function not the method
func("yummy")  # "yummy cheese"

@override¶

You may also ‘overload’ functions using the @override decorator. This one overrides an list of callables or Function (function wrapper class of overloadlib.py.) via a given new ‘parent’ function.

def func_str(var: str) -> str:
    return "I am a string"

def func_int(var: int) -> str:
    return "I am an integer"

@overload
def func_both(var_1: int, var_2: str) -> str:
    return var_2 * var_1

@override(funcs=[func_str, func_int, func_both])  # callables and `Function` are given
def new_func(fl: float) -> str:
    return "Float parameter"

Possible calls could now look like this:

new_func(1.0) == "Float parameter"  # True
new_func("a") == func_str("a") == "I am a string"  # True
new_func(1) == func_int(1) == "I am an integer"  # True
new_func(1, "a") == func_both(1, "a") == "a"  # True

Overriding Function’s (callables that are decorated with @overload) overrides every version of that Function:

@dataclass
class Some:
    text: str = "Hello"

@overload
def func(str_1: str) -> str:
    return str_1

@func.add
def _(obj: Some) -> str:
    return obj.text

@overload
def func() -> str:
    return "Functions don't need to have arguments."

# adds all previously defined overloads/'version' of `func` to `new`
@override(funcs=[func])
def new(str_1: str, int_1: int) -> str:
    return str_1 * int_1

assert new("a") == "a" == func("a")
assert new(Some()) == "Hello" == func(Some())
assert new() == "Functions don't need to have arguments." == func()
assert new("house", 2) == "househouse"

@<Function>.add¶

You can always add a new callable to an existing overloaded callable <func> using the @<func>.add decorator:

@overload
def some_func(str_1: str, int_1: int) -> str:
    return str_1 + str(int_1)

@some_func.add
def _(str_1: str) -> str:
    return str_1

@some_func.add
def name_does_not_matter() -> str:
    return "I return some text."

@some_func.add
def _(str_1: str, str_2: str) -> str:
    return str_1 + str_2

assert some_func("This is a number: ", 10) == "This is a number: 10"
assert some_func("cheese") == "cheese"
assert some_func(Some()) == "Hello"

The name of the callable’s you are adding don’t matter and you can also always use the same name, when adding. However, as using the same name for added functions, clashes with [no-redef] error of mypy, it is recommended to use different ones (this also increases the readability of the code). 1

Usage of @override and @<Function>.add is recommended over usage of @overload only, when working with static type checkers like mypy.

1: It should also be stressed, that @<func>.add only works with a previously with @overload decorated function `.

func_versions_info¶

If you want to get all versions of a certain function <myfunc>, use func_versions_info(<myfunc>), e.g.

>>> print(func_versions_info(new_func))

Following overloads of 'new_func' exist:
(__main__.new_func):
         def new_func(var: str):
                ...
(__main__.new_func):
         def new_func(var: int):
                ...
(__main__.new_func):
         def new_func(var_1: int, var_2: str):
                ...
(__main__.new_func):
         def new_func(fl: float):
                ...

Common Mistakes and Limitations¶

Overloading using overload raises problems with mypy. This can be circumvented using @override (or @<func>.add) instead of @overload.

Reference¶

overloadlib.__main__

overloadlib.main¶

__main__ of overloadlib.

overloadlib.__main__.version_callback()¶

Print the version of the package.

Return type: Any

Contributor Guide¶

Thank you for your interest in improving this project. This project is open-source under the MIT license and welcomes contributions in the form of bug reports, feature requests, and pull requests.

Here is a list of important resources for contributors:

How to report a bug¶

Report bugs on the Issue Tracker.

When filing an issue, make sure to answer these questions:

Which operating system and Python version are you using?
Which version of this project are you using?
What did you do?
What did you expect to see?
What did you see instead?

The best way to get your bug fixed is to provide a test case, and/or steps to reproduce the issue.

How to request a feature¶

Request features on the Issue Tracker.

How to set up your development environment¶

You need Python 3.6+ and the following tools:

Install the package with development requirements:

$ poetry install

You can now run an interactive Python session, or the command-line interface:

$ poetry run python
$ poetry run overloadlib

How to test the project¶

Run the full test suite:

$ nox

List the available Nox sessions:

$ nox --list-sessions

You can also run a specific Nox session. For example, invoke the unit test suite like this:

$ nox --session=tests

Unit tests are located in the tests directory, and are written using the pytest testing framework.

How to submit changes¶

Open a pull request to submit changes to this project.

Your pull request needs to meet the following guidelines for acceptance:

The Nox test suite must pass without errors and warnings.
Include unit tests. This project maintains 100% code coverage.
If your changes add functionality, update the documentation accordingly.

Feel free to submit early, though—we can always iterate on this.

To run linting and code formatting checks before commiting your change, you can install pre-commit as a Git hook by running the following command:

$ nox --session=pre-commit -- install

It is recommended to open an issue before starting work on anything. This will allow a chance to talk it over with the owners and validate your approach.

Contributor Covenant Code of Conduct¶

Our Pledge¶

We as members, contributors, and leaders pledge to make participation in our community a harassment-free experience for everyone, regardless of age, body size, visible or invisible disability, ethnicity, sex characteristics, gender identity and expression, level of experience, education, socio-economic status, nationality, personal appearance, race, religion, or sexual identity and orientation.

We pledge to act and interact in ways that contribute to an open, welcoming, diverse, inclusive, and healthy community.

Our Standards¶

Examples of behavior that contributes to a positive environment for our community include:

Demonstrating empathy and kindness toward other people
Being respectful of differing opinions, viewpoints, and experiences
Giving and gracefully accepting constructive feedback
Accepting responsibility and apologizing to those affected by our mistakes, and learning from the experience
Focusing on what is best not just for us as individuals, but for the overall community

Examples of unacceptable behavior include:

The use of sexualized language or imagery, and sexual attention or advances of any kind
Trolling, insulting or derogatory comments, and personal or political attacks
Public or private harassment
Publishing others’ private information, such as a physical or email address, without their explicit permission
Other conduct which could reasonably be considered inappropriate in a professional setting

Enforcement Responsibilities¶

Community leaders are responsible for clarifying and enforcing our standards of acceptable behavior and will take appropriate and fair corrective action in response to any behavior that they deem inappropriate, threatening, offensive, or harmful.

Community leaders have the right and responsibility to remove, edit, or reject comments, commits, code, wiki edits, issues, and other contributions that are not aligned to this Code of Conduct, and will communicate reasons for moderation decisions when appropriate.

Scope¶

This Code of Conduct applies within all community spaces, and also applies when an individual is officially representing the community in public spaces. Examples of representing our community include using an official e-mail address, posting via an official social media account, or acting as an appointed representative at an online or offline event.

Enforcement¶

Instances of abusive, harassing, or otherwise unacceptable behavior may be reported to the community leaders responsible for enforcement at nicdomgesing@gmail.com. All complaints will be reviewed and investigated promptly and fairly.

All community leaders are obligated to respect the privacy and security of the reporter of any incident.

Enforcement Guidelines¶

Community leaders will follow these Community Impact Guidelines in determining the consequences for any action they deem in violation of this Code of Conduct:

1. Correction¶

Community Impact: Use of inappropriate language or other behavior deemed unprofessional or unwelcome in the community.

Consequence: A private, written warning from community leaders, providing clarity around the nature of the violation and an explanation of why the behavior was inappropriate. A public apology may be requested.

2. Warning¶

Community Impact: A violation through a single incident or series of actions.

Consequence: A warning with consequences for continued behavior. No interaction with the people involved, including unsolicited interaction with those enforcing the Code of Conduct, for a specified period of time. This includes avoiding interactions in community spaces as well as external channels like social media. Violating these terms may lead to a temporary or permanent ban.

3. Temporary Ban¶

Community Impact: A serious violation of community standards, including sustained inappropriate behavior.

Consequence: A temporary ban from any sort of interaction or public communication with the community for a specified period of time. No public or private interaction with the people involved, including unsolicited interaction with those enforcing the Code of Conduct, is allowed during this period. Violating these terms may lead to a permanent ban.

4. Permanent Ban¶

Community Impact: Demonstrating a pattern of violation of community standards, including sustained inappropriate behavior, harassment of an individual, or aggression toward or disparagement of classes of individuals.

Consequence: A permanent ban from any sort of public interaction within the community.

Attribution¶

This Code of Conduct is adapted from the Contributor Covenant, version 2.0, available at https://www.contributor-covenant.org/version/2/0/code_of_conduct.html.

Community Impact Guidelines were inspired by Mozilla’s code of conduct enforcement ladder.

For answers to common questions about this code of conduct, see the FAQ at https://www.contributor-covenant.org/faq. Translations are available at https://www.contributor-covenant.org/translations.

MIT License¶

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

The software is provided “as is”, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.

Overloadlib¶

Features¶

Requirements¶

Installation¶

Uninstall¶

Usage¶

Contributing¶

License¶

Issues¶

Credits¶

Usage¶

@overload¶

@override¶

@<Function>.add¶

func_versions_info¶

Common Mistakes and Limitations¶

Reference¶

overloadlib.__main__¶

Contributor Guide¶

How to report a bug¶

How to request a feature¶

How to set up your development environment¶

How to test the project¶

How to submit changes¶

Contributor Covenant Code of Conduct¶

Our Pledge¶

Our Standards¶

Enforcement Responsibilities¶

Scope¶

Enforcement¶

Enforcement Guidelines¶

1. Correction¶

2. Warning¶

3. Temporary Ban¶

4. Permanent Ban¶

Attribution¶

MIT License¶

overloadlib.main¶