OOP Extensions

What is OOP Extensions ?

OOP Extensions is a set of utilities for object oriented programming which is missing on Python core libraries.

Usage

oop_ext brings a set of object oriented utilities, it supports the concept of interfaces, abstract/overridable methods and more. oop_ext carefully checks that implementations have the same method signatures as the interface it implements and raises exceptions otherwise.

Here's a simple example showing some nice features:

from oop_ext.interface import Interface, ImplementsInterface


class IDisposable(Interface):
    def dispose(self):
        """
        Clears this object
        """

    def is_disposed(self) -> bool:
        """
        Returns True if the object has been cleared
        """


@ImplementsInterface(IDisposable)
class MyObject(Disposable):
    def __init__(self):
        super().__init__()
        self._data = [0] * 100
        self._is_disposed = False

    def is_disposed(self) -> bool:
        return self._is_disposed

    def dispose(self):
        self._is_disposed = True
        self._data = []

If any of the two methods in MyObject are not implemented or have differ signatures than the ones declared in IDisposable, the ImplementsInterface decorator will raise an error during import.

Arbitrary objects can be verified if they implement a certain interface by using IsImplementation:

from oop_ext.interface import IsImplementation

my_object = MyObject()
if IsImplementation(my_object, IDisposable):
    # my_object is guaranteed to implement IDisposable completely
    my_object.dispose()

Alternatively you can assert that an object implements the desired interface with AssertImplements:

from oop_ext.interface import AssertImplements

my_object = MyObject()
AssertImplements(my_object, IDisposable)
my_object.dispose()

Type Checking

As of 1.1.0, oop-ext includes inline type annotations and exposes them to user programs.

If you are running a type checker such as mypy on your tests, you may start noticing type errors indicating incorrect usage. If you run into an error that you believe to be incorrect, please let us know in an issue.

The types were developed against mypy version 0.800.

See the docs for more information.

Contributing

For guidance on setting up a development environment and how to make a contribution to oop_ext, see the contributing guidelines.

Release

A reminder for the maintainers on how to make a new release.

Note that the VERSION should follow the semantic versioning as X.Y.Z (e.g. v1.0.5).

1. Create a release-VERSION branch from upstream/master.
2. Update CHANGELOG.rst.
3. Push a branch with the changes.
4. Once all builds pass, push a VERSION tag to upstream.
5. Merge the PR.