Skip to main content

A tool for automated delegation with abstract base classes

Project description

abc-delegation

A tool for automated delegation with abstract base classes.

This metaclass enables creation of delegating classes inheriting from an abstract base class.

This technique is impossible with regular __getattr__ approach for delegation, so normally, you would have to define every delegated method explicitly. Not any more

Installation: pip install abc-delegation

Basic usage:

from abc import ABCMeta

from abc_delegation import delegation_metaclass

class A(metaclass=ABCMeta):
    @abstractmethod
    def bar(self):
        pass

    @abstractmethod
    def foo(self):
        pass

class B:
    def bar(self):
        return "B bar"

    def foo(self):
        return "B foo"

class C(A, metaclass=delegation_metaclass("my_delegate")):
    def __init__(self, b):
        self.my_delegate = b

    def foo(self):
        return "C foo"

c = C(B())
assert c.foo() == "C foo"
assert c.bar() == "B bar"

Multiple delegates:

from abc import ABCMeta

from abc_delegation import multi_delegation_metaclass


class A(metaclass=ABCMeta):
    @abstractmethod
    def bar(self):
        pass

    @abstractmethod
    def foo(self):
        pass

    @abstractmethod
    def baz(self):
        pass

class B:
    def bar(self):
        return "B bar"

    def foo(self):
        return "B foo"

class X:
    def baz(self):
        return "X baz"

class C(A, metaclass=multi_delegation_metaclass("_delegate1", "_delegate2")):
    def __init__(self, d1, d2):
        self._delegate1 = d1
        self._delegate2 = d2

    def foo(self):
        return "C foo"

c = C(B(), X())
assert c.bar() == "B bar"
assert c.foo() == "C foo"
assert c.baz() == "X baz"

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

abc-delegation-0.2.2.tar.gz (3.0 kB view hashes)

Uploaded Source

Built Distribution

abc_delegation-0.2.2-py3-none-any.whl (3.2 kB view hashes)

Uploaded Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page