Mark abstract base classes and methods

newsfragments/4503.feature.rst

@@ -0,0 +1 @@
+Mark abstract base classes and methods with `abc.ABC` and `abc.abstractmethod` -- by :user:`Avasam`

pkg_resources/__init__.py

@@ -22,6 +22,7 @@
 
 from __future__ import annotations
 
+from abc import ABC
 import sys
 
 if sys.version_info < (3, 8):  # noqa: UP036 # Check for unsupported versions
@@ -311,7 +312,7 @@ def get_supported_platform():
 ]
 
 
-class ResolutionError(Exception):
+class ResolutionError(Exception, ABC):
     """Abstract base for dependency resolution errors"""
 
     def __repr__(self):

setuptools/__init__.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+from abc import ABC, abstractmethod
 import functools
 import os
 import re
@@ -119,7 +120,7 @@ def setup(**attrs):
     _Command = monkey.get_unpatched(distutils.core.Command)
 
 
-class Command(_Command):
+class Command(_Command, ABC):
     """
     Setuptools internal actions are organized using a *command design pattern*.
     This means that each action (or group of closely related actions) executed during
@@ -132,42 +133,25 @@ class Command(_Command):
     When creating a new command from scratch, custom defined classes **SHOULD** inherit
     from ``setuptools.Command`` and implement a few mandatory methods.
     Between these mandatory methods, are listed:
-
-    .. method:: initialize_options(self)
-
-        Set or (reset) all options/attributes/caches used by the command
-        to their default values. Note that these values may be overwritten during
-        the build.
-
-    .. method:: finalize_options(self)
-
-        Set final values for all options/attributes used by the command.
-        Most of the time, each option/attribute/cache should only be set if it does not
-        have any value yet (e.g. ``if self.attr is None: self.attr = val``).
-
-    .. method:: run(self)
-
-        Execute the actions intended by the command.
-        (Side effects **SHOULD** only take place when ``run`` is executed,
-        for example, creating new files or writing to the terminal output).
+    :meth:`initialize_options`, :meth:`finalize_options` and :meth:`run`.
 
     A useful analogy for command classes is to think of them as subroutines with local
-    variables called "options".  The options are "declared" in ``initialize_options()``
-    and "defined" (given their final values, aka "finalized") in ``finalize_options()``,
+    variables called "options".  The options are "declared" in :meth:`initialize_options`
+    and "defined" (given their final values, aka "finalized") in :meth:`finalize_options`,
     both of which must be defined by every command class. The "body" of the subroutine,
-    (where it does all the work) is the ``run()`` method.
-    Between ``initialize_options()`` and ``finalize_options()``, ``setuptools`` may set
+    (where it does all the work) is the :meth:`run` method.
+    Between :meth:`initialize_options` and :meth:`finalize_options`, ``setuptools`` may set
     the values for options/attributes based on user's input (or circumstance),
     which means that the implementation should be careful to not overwrite values in
-    ``finalize_options`` unless necessary.
+    :meth:`finalize_options` unless necessary.
 
     Please note that other commands (or other parts of setuptools) may also overwrite
     the values of the command's options/attributes multiple times during the build
     process.
-    Therefore it is important to consistently implement ``initialize_options()`` and
-    ``finalize_options()``. For example, all derived attributes (or attributes that
+    Therefore it is important to consistently implement :meth:`initialize_options` and
+    :meth:`finalize_options`. For example, all derived attributes (or attributes that
     depend on the value of other attributes) **SHOULD** be recomputed in
-    ``finalize_options``.
+    :meth:`finalize_options`.
 
     When overwriting existing commands, custom defined classes **MUST** abide by the
     same APIs implemented by the original class. They also **SHOULD** inherit from the
@@ -238,6 +222,33 @@ def reinitialize_command(
         vars(cmd).update(kw)
         return cmd
 
+    @abstractmethod
+    def initialize_options(self) -> None:
+        """
+        Set or (reset) all options/attributes/caches used by the command
+        to their default values. Note that these values may be overwritten during
+        the build.
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def finalize_options(self) -> None:
+        """
+        Set final values for all options/attributes used by the command.
+        Most of the time, each option/attribute/cache should only be set if it does not
+        have any value yet (e.g. ``if self.attr is None: self.attr = val``).
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def run(self) -> None:
+        """
+        Execute the actions intended by the command.
+        (Side effects **SHOULD** only take place when :meth:`run` is executed,
+        for example, creating new files or writing to the terminal output).
+        """
+        raise NotImplementedError
+
 
 def _find_all_simple(path):
     """

setuptools/command/setopt.py

@@ -1,3 +1,4 @@
+from abc import ABC, abstractmethod
 from distutils.util import convert_path
 from distutils import log
 from distutils.errors import DistutilsOptionError
@@ -68,7 +69,7 @@ def edit_config(filename, settings, dry_run=False):
             opts.write(f)
 
 
-class option_base(Command):
+class option_base(Command, ABC):
     """Abstract base class for commands that mess with config files"""
 
     user_options = [
@@ -103,6 +104,10 @@ def finalize_options(self):
             )
         (self.filename,) = filenames
 
+    @abstractmethod
+    def run(self) -> None:
+        raise NotImplementedError
+
 
 class setopt(option_base):
     """Save command-line options to a file"""

setuptools/sandbox.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from abc import ABC
 import os
 import sys
 import tempfile
@@ -265,7 +266,7 @@ def run_setup(setup_script, args):
             # Normal exit, just return
 
 
-class AbstractSandbox:
+class AbstractSandbox(ABC):
     """Wrap 'os' module and 'open()' builtin for virtualizing setup scripts"""
 
     _active = False