runtime-final's Introduction

amulet-runtime-final

Declare final Python classes and methods at runtime.

This module provides a decorator based interface to declare final classes and methods that are enforced at runtime. This module is inspired by and is compatible with typing.final. See PEP-591 for more details on this topic.

Installation

Python 3.6 or higher is required.

You can simply install this module from pip.

python -m pip install amulet-runtime-final

Usage

The main component of this module is the final decorator that can be used to decorate classes and methods inside a class. As such:

Classes decorated with @final cannot be subclassed.
Methods decorated with @final cannot be overriden in subclasses.

For example with classes:

from runtime_final import final

@final
class Foo:
    ...

class Bar(Foo):  # Raises RuntimeError
    ...

And with methods:

from runtime_final import final

class Foo:
    @final
    def foo(self):
        ...

class Bar(Foo):
    def foo(self):  # Raises RuntimeError
        ...

And with other decorators:

from runtime_final import final

class Foo:
    @final
    @property
    def foo(self):
        ...
    
    @final
    @staticmethod
    def bar():
        ...
    
    @final
    @classmethod
    def baz(cls):
        ...

class Bar(Foo):
    @property
    def foo(self):  # Raises RuntimeError
        ...

    @staticmethod
    def bar():  # Raises RuntimeError
        ...
    
    @classmethod
    def baz(cls):  # Raises RuntimeError
        ...

With property setters:

from runtime_final import final

class Foo:
    @property
    def foo(self):
        ...
    
    # Note that the `final` decorator must only be applied to the last definition.
    
    @final
    @foo.setter
    def foo(self, foo):
        ...

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