Drop support for python 2.7, 3.4, and 3.5

.github/workflows/test.yml

@@ -18,9 +18,8 @@ jobs:
       fail-fast: false
       matrix:
         os: [Ubuntu, Windows, macOS]
-        # Python 3.4 is not available from actions/setup-python@v2.
         python_version:
-          ["2.7", "3.5", "3.6", "3.7", "3.8", "3.9", "pypy2", "pypy3"]
+          ["3.6", "3.7", "3.8", "3.9", "pypy3"]
         exclude:
           # This is failing due to pip not being in the virtual environment.
           # https://github.com/pypa/packaging/runs/424785871#step:7:9
@@ -35,26 +34,6 @@ jobs:
         with:
           python-version: ${{ matrix.python_version }}
 
-      # Set `python` to a recent 3.x version if we're not testing Python 3.6+.
-      #    Why? Nox needs Python 3.5+ and everyone likes f-strings.
-      - uses: actions/setup-python@v2
-        name: Install Python 3.x
-        with:
-          python-version: 3.x
-        if: >
-          (
-            matrix.python_version == '2.7' ||
-            matrix.python_version == 'pypy2' ||
-            matrix.python_version == '3.5'
-          )
-
-      # Workaround https://github.com/theacodes/nox/issues/250
-      - name: Workaround for Windows Python 2.7
-        # This is in PATH, so nox resolves to it - but then subsequent steps fail.
-        run: rm C:/ProgramData/Chocolatey/bin/python2.7.exe
-        shell: bash
-        if: runner.os == 'Windows' && matrix.python_version == '2.7'
-
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip

.pre-commit-config.yaml

@@ -13,10 +13,6 @@ repos:
       - id: mypy
         exclude: '^(docs|tasks|tests)|setup\.py'
         args: []
-      - id: mypy
-        name: mypy for Python 2
-        exclude: '^(docs|tasks|tests)|setup\.py|noxfile\.py'
-        args: ["--py2"]
 
   - repo: https://github.com/psf/black
     rev: 19.3b0

.travis.yml

@@ -4,16 +4,8 @@ python: 3.8
 
 matrix:
   include:
-    - python: 2.7
-      env: NOXSESSION=tests-2.7
-    - python: pypy
-      env: NOXSESSION=tests-pypy
     - python: pypy3
       env: NOXSESSION=tests-pypy3
-    - python: 3.4
-      env: NOXSESSION=tests-3.4
-    - python: 3.5
-      env: NOXSESSION=tests-3.5
     - python: 3.6
       env: NOXSESSION=tests-3.6
     - python: 3.7

CHANGELOG.rst

@@ -4,7 +4,7 @@ Changelog
 *unreleased*
 ~~~~~~~~~~~~
 
-No unreleased changes.
+* `packaging` is now only compatible with Python 3.6 and above.
 
 20.9 - 2021-01-29
 ~~~~~~~~~~~~~~~~~

docs/conf.py

@@ -1,8 +1,6 @@
-# -*- coding: utf-8 -*-
 # This file is dual licensed under the terms of the Apache License, Version
 # 2.0, and the BSD License. See the LICENSE file in the root of this repository
 # for complete details.
-from __future__ import absolute_import, division, print_function
 
 import os
 import sys

docs/development/getting-started.rst

@@ -30,13 +30,10 @@ each supported Python version and run the tests. For example:
     $ nox -s tests
     ...
     nox > Ran multiple sessions:
-    nox > * tests-2.7: success
-    nox > * tests-3.4: skipped
-    nox > * tests-3.5: success
     nox > * tests-3.6: success
     nox > * tests-3.7: success
     nox > * tests-3.8: success
-    nox > * tests-pypy: skipped
+    nox > * tests-3.9: success
     nox > * tests-pypy3: skipped
 
 You may not have all the required Python versions installed, in which case you

noxfile.py

@@ -20,7 +20,7 @@
 nox.options.reuse_existing_virtualenvs = True
 
 
-@nox.session(python=["2.7", "3.4", "3.5", "3.6", "3.7", "3.8", "3.9", "pypy", "pypy3"])
+@nox.session(python=["3.6", "3.7", "3.8", "3.9", "pypy3"])
 def tests(session):
     def coverage(*args):
         session.run("python", "-m", "coverage", *args)

packaging/__about__.py

@@ -1,7 +1,6 @@
 # This file is dual licensed under the terms of the Apache License, Version
 # 2.0, and the BSD License. See the LICENSE file in the root of this repository
 # for complete details.
-from __future__ import absolute_import, division, print_function
 
 __all__ = [
     "__title__",

packaging/__init__.py

@@ -1,7 +1,6 @@
 # This file is dual licensed under the terms of the Apache License, Version
 # 2.0, and the BSD License. See the LICENSE file in the root of this repository
 # for complete details.
-from __future__ import absolute_import, division, print_function
 
 from .__about__ import (
     __author__,

packaging/_structures.py

@@ -1,10 +1,9 @@
 # This file is dual licensed under the terms of the Apache License, Version
 # 2.0, and the BSD License. See the LICENSE file in the root of this repository
 # for complete details.
-from __future__ import absolute_import, division, print_function
 
 
-class InfinityType(object):
+class InfinityType:
     def __repr__(self):
         # type: () -> str
         return "Infinity"
@@ -45,7 +44,7 @@ def __neg__(self):
 Infinity = InfinityType()
 
 
-class NegativeInfinityType(object):
+class NegativeInfinityType:
     def __repr__(self):
         # type: () -> str
         return "-Infinity"

packaging/markers.py

@@ -1,7 +1,6 @@
 # This file is dual licensed under the terms of the Apache License, Version
 # 2.0, and the BSD License. See the LICENSE file in the root of this repository
 # for complete details.
-from __future__ import absolute_import, division, print_function
 
 import operator
 import os
@@ -20,7 +19,6 @@
     stringStart,
 )
 
-from ._compat import string_types
 from ._typing import TYPE_CHECKING
 from .specifiers import InvalidSpecifier, Specifier
 
@@ -58,7 +56,7 @@ class UndefinedEnvironmentName(ValueError):
     """
 
 
-class Node(object):
+class Node:
     def __init__(self, value):
         # type: (Any) -> None
         self.value = value
@@ -69,7 +67,7 @@ def __str__(self):
 
     def __repr__(self):
         # type: () -> str
-        return "<{0}({1!r})>".format(self.__class__.__name__, str(self))
+        return f"<{self.__class__.__name__}('{self}')>"
 
     def serialize(self):
         # type: () -> str
@@ -85,7 +83,7 @@ def serialize(self):
 class Value(Node):
     def serialize(self):
         # type: () -> str
-        return '"{0}"'.format(self)
+        return f'"{self}"'
 
 
 class Op(Node):
@@ -162,7 +160,7 @@ def _coerce_parse_result(results):
 def _format_marker(marker, first=True):
     # type: (Union[List[str], Tuple[Node, ...], str], Optional[bool]) -> str
 
-    assert isinstance(marker, (list, tuple, string_types))
+    assert isinstance(marker, (list, tuple, str))
 
     # Sometimes we have a structure like [[...]] which is a single item list
     # where the single item is itself it's own list. In that case we want skip
@@ -210,14 +208,12 @@ def _eval_op(lhs, op, rhs):
 
     oper = _operators.get(op.serialize())  # type: Optional[Operator]
     if oper is None:
-        raise UndefinedComparison(
-            "Undefined {0!r} on {1!r} and {2!r}.".format(op, lhs, rhs)
-        )
+        raise UndefinedComparison(f"Undefined {op!r} on {lhs!r} and {rhs!r}.")
 
     return oper(lhs, rhs)
 
 
-class Undefined(object):
+class Undefined:
     pass
 
 
@@ -230,7 +226,7 @@ def _get_env(environment, name):
 
     if isinstance(value, Undefined):
         raise UndefinedEnvironmentName(
-            "{0!r} does not exist in evaluation environment.".format(name)
+            f"{name!r} does not exist in evaluation environment."
         )
 
     return value
@@ -241,7 +237,7 @@ def _evaluate_markers(markers, environment):
     groups = [[]]  # type: List[List[bool]]
 
     for marker in markers:
-        assert isinstance(marker, (list, tuple, string_types))
+        assert isinstance(marker, (list, tuple, str))
 
         if isinstance(marker, list):
             groups[-1].append(_evaluate_markers(marker, environment))
@@ -275,16 +271,8 @@ def format_full_version(info):
 
 def default_environment():
     # type: () -> Dict[str, str]
-    if hasattr(sys, "implementation"):
-        # Ignoring the `sys.implementation` reference for type checking due to
-        # mypy not liking that the attribute doesn't exist in Python 2.7 when
-        # run with the `--py27` flag.
-        iver = format_full_version(sys.implementation.version)  # type: ignore
-        implementation_name = sys.implementation.name  # type: ignore
-    else:
-        iver = "0"
-        implementation_name = ""
-
+    iver = format_full_version(sys.implementation.version)
+    implementation_name = sys.implementation.name
     return {
         "implementation_name": implementation_name,
         "implementation_version": iver,
@@ -300,24 +288,24 @@ def default_environment():
     }
 
 
-class Marker(object):
+class Marker:
     def __init__(self, marker):
         # type: (str) -> None
         try:
             self._markers = _coerce_parse_result(MARKER.parseString(marker))
         except ParseException as e:
-            err_str = "Invalid marker: {0!r}, parse error at {1!r}".format(
-                marker, marker[e.loc : e.loc + 8]
+            raise InvalidMarker(
+                f"Invalid marker: {marker!r}, parse error at "
+                f"{marker[e.loc : e.loc + 8]!r}"
             )
-            raise InvalidMarker(err_str)
 
     def __str__(self):
         # type: () -> str
         return _format_marker(self._markers)
 
     def __repr__(self):
         # type: () -> str
-        return "<Marker({0!r})>".format(str(self))
+        return f"<Marker('{self}')>"
 
     def evaluate(self, environment=None):
         # type: (Optional[Dict[str, str]]) -> bool