Reduce import time

src/packaging/_logging.py

@@ -0,0 +1,17 @@
+# 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 annotations
+
+from functools import lru_cache
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from logging import Logger
+
+
+@lru_cache(maxsize=None)
+def get_logger(name: str) -> Logger:
+    import logging
+
+    return logging.getLogger(name)

src/packaging/_manylinux.py

@@ -6,7 +6,6 @@
 import os
 import re
 import sys
-import warnings
 from typing import Generator, Iterator, NamedTuple, Sequence
 
 from ._elffile import EIClass, EIData, ELFFile, EMachine
@@ -152,6 +151,8 @@ def _parse_glibc_version(version_str: str) -> tuple[int, int]:
     """
     m = re.match(r"(?P<major>[0-9]+)\.(?P<minor>[0-9]+)", version_str)
     if not m:
+        import warnings
+
         warnings.warn(
             f"Expected glibc version with 2 components major.minor,"
             f" got: {version_str}",

src/packaging/_musllinux.py

@@ -7,7 +7,6 @@
 
 import functools
 import re
-import subprocess
 import sys
 from typing import Iterator, NamedTuple, Sequence
 
@@ -48,6 +47,9 @@ def _get_musl_version(executable: str) -> _MuslVersion | None:
         return None
     if ld is None or "musl" not in ld:
         return None
+
+    import subprocess
+
     proc = subprocess.run([ld], stderr=subprocess.PIPE, text=True)
     return _parse_musl_version(proc.stderr)
 

src/packaging/_tokenizer.py

@@ -2,17 +2,18 @@
 
 import contextlib
 import re
-from dataclasses import dataclass
 from typing import Iterator, NoReturn
 
 from .specifiers import Specifier
 
 
-@dataclass
 class Token:
-    name: str
-    text: str
-    position: int
+    __slots__ = ("name", "text", "position")
+
+    def __init__(self, name: str, text: str, position: int) -> None:
+        self.name = name
+        self.text = text
+        self.position = position
 
 
 class ParserSyntaxError(Exception):

src/packaging/markers.py

@@ -5,7 +5,6 @@
 
 import operator
 import os
-import platform
 import sys
 from typing import TYPE_CHECKING, Any, Callable
 
@@ -170,6 +169,8 @@ def format_full_version(info: sys._version_info) -> str:
 
 
 def default_environment() -> dict[str, str]:
+    import platform
+
     iver = format_full_version(sys.implementation.version)
     implementation_name = sys.implementation.name
     return {

src/packaging/tags.py

@@ -3,23 +3,17 @@
 # for complete details.
 from __future__ import annotations
 
-import logging
-import platform
 import re
 import struct
-import subprocess
 import sys
-import sysconfig
 from importlib.machinery import EXTENSION_SUFFIXES
 from typing import TYPE_CHECKING, Iterable, Iterator, cast
 
-from . import _manylinux, _musllinux
+from . import _logging, _manylinux, _musllinux
 
 if TYPE_CHECKING:
     from ._types import MacVersion, PythonVersion
 
-logger = logging.getLogger(__name__)
-
 INTERPRETER_SHORT_NAMES: dict[str, str] = {
     "python": "py",  # Generic.
     "cpython": "cp",
@@ -103,9 +97,11 @@ def parse_tag(tag: str) -> frozenset[Tag]:
 
 
 def _get_config_var(name: str, warn: bool = False) -> int | str | None:
+    import sysconfig
+
     value: int | str | None = sysconfig.get_config_var(name)
     if value is None and warn:
-        logger.debug(
+        _logging.get_logger(__name__).debug(
             "Config variable '%s' is unset, Python ABI tag may be incorrect", name
         )
     return value
@@ -399,10 +395,14 @@ def mac_platforms(
     generate platform tags for. Both parameters default to the appropriate value
     for the current system.
     """
+    import platform
+
     version_str, _, cpu_arch = platform.mac_ver()
     if version is None:
         version = cast("MacVersion", tuple(map(int, version_str.split(".")[:2])))
         if version == (10, 16):
+            import subprocess
+
             # When built against an older macOS SDK, Python will report macOS 10.16
             # instead of the real version.
             version_str = subprocess.run(
@@ -477,6 +477,8 @@ def mac_platforms(
 
 
 def _linux_platforms(is_32bit: bool = _32_BIT_INTERPRETER) -> Iterator[str]:
+    import sysconfig
+
     linux = _normalize_string(sysconfig.get_platform())
     if not linux.startswith("linux_"):
         # we should never be here, just yield the sysconfig one and return
@@ -496,16 +498,18 @@ def _linux_platforms(is_32bit: bool = _32_BIT_INTERPRETER) -> Iterator[str]:
 
 
 def _generic_platforms() -> Iterator[str]:
+    import sysconfig
+
     yield _normalize_string(sysconfig.get_platform())
 
 
 def platform_tags() -> Iterator[str]:
     """
     Provides the platform tags for this installation.
     """
-    if platform.system() == "Darwin":
+    if sys.platform == "darwin":
         return mac_platforms()
-    elif platform.system() == "Linux":
+    elif sys.platform.lower().startswith("linux"):
         return _linux_platforms()
     else:
         return _generic_platforms()

tests/test_musllinux.py

@@ -5,7 +5,6 @@
 import pretend
 import pytest
 
-from packaging import _musllinux
 from packaging._musllinux import _get_musl_version, _MuslVersion, _parse_musl_version
 
 MUSL_AMD64 = "musl libc (x86_64)\nVersion 1.2.2\n"
@@ -63,7 +62,7 @@ def mock_run(*args, **kwargs):
         return collections.namedtuple("Proc", "stderr")(output)
 
     run_recorder = pretend.call_recorder(mock_run)
-    monkeypatch.setattr(_musllinux.subprocess, "run", run_recorder)
+    monkeypatch.setattr(subprocess, "run", run_recorder)
 
     assert _get_musl_version(str(executable)) == version
 

tests/test_tags.py

@@ -11,6 +11,7 @@
 except ImportError:
     ctypes = None
 import importlib
+import logging
 import os
 import pathlib
 import platform
@@ -22,7 +23,7 @@
 import pretend
 import pytest
 
-from packaging import tags
+from packaging import _logging, tags
 from packaging._manylinux import _GLibCVersion
 from packaging._musllinux import _MuslVersion
 
@@ -344,13 +345,19 @@ def teardown_method(self):
 
     def test_get_config_var_does_not_log(self, monkeypatch):
         debug = pretend.call_recorder(lambda *a: None)
-        monkeypatch.setattr(tags.logger, "debug", debug)
+        logger = logging.getLogger(__name__)
+        loggers = {"packaging.tags": logger}
+        monkeypatch.setattr(logger, "debug", debug)
+        monkeypatch.setattr(_logging, "get_logger", lambda name: loggers[name])
         tags._get_config_var("missing")
         assert debug.calls == []
 
     def test_get_config_var_does_log(self, monkeypatch):
         debug = pretend.call_recorder(lambda *a: None)
-        monkeypatch.setattr(tags.logger, "debug", debug)
+        logger = logging.getLogger(__name__)
+        loggers = {"packaging.tags": logger}
+        monkeypatch.setattr(logger, "debug", debug)
+        monkeypatch.setattr(_logging, "get_logger", lambda name: loggers[name])
         tags._get_config_var("missing", warn=True)
         assert debug.calls == [
             pretend.call(
@@ -620,14 +627,14 @@ def test_linux_not_linux(self, monkeypatch):
 @pytest.mark.parametrize(
     "platform_name,dispatch_func",
     [
-        ("Darwin", "mac_platforms"),
-        ("Linux", "_linux_platforms"),
-        ("Generic", "_generic_platforms"),
+        ("darwin", "mac_platforms"),
+        ("linux", "_linux_platforms"),
+        ("generic", "_generic_platforms"),
     ],
 )
 def test_platform_tags(platform_name, dispatch_func, monkeypatch):
     expected = ["sillywalk"]
-    monkeypatch.setattr(platform, "system", lambda: platform_name)
+    monkeypatch.setattr(sys, "platform", platform_name)
     monkeypatch.setattr(tags, dispatch_func, lambda: expected)
     assert tags.platform_tags() == expected
 
@@ -1180,7 +1187,7 @@ def test_mac_cpython(self, mock_interpreter_name, monkeypatch):
         if mock_interpreter_name("CPython"):
             monkeypatch.setattr(tags, "_cpython_abis", lambda *a: ["cp33m"])
         if platform.system() != "Darwin":
-            monkeypatch.setattr(platform, "system", lambda: "Darwin")
+            monkeypatch.setattr(sys, "platform", "darwin")
             monkeypatch.setattr(tags, "mac_platforms", lambda: ["macosx_10_5_x86_64"])
         abis = tags._cpython_abis(sys.version_info[:2])
         platforms = list(tags.mac_platforms())
@@ -1197,7 +1204,7 @@ def test_windows_cpython(self, mock_interpreter_name, monkeypatch):
         if mock_interpreter_name("CPython"):
             monkeypatch.setattr(tags, "_cpython_abis", lambda *a: ["cp33m"])
         if platform.system() != "Windows":
-            monkeypatch.setattr(platform, "system", lambda: "Windows")
+            monkeypatch.setattr(sys, "platform", "win32")
             monkeypatch.setattr(tags, "_generic_platforms", lambda: ["win_amd64"])
         abis = list(tags._cpython_abis(sys.version_info[:2]))
         platforms = list(tags._generic_platforms())
@@ -1215,7 +1222,7 @@ def test_linux_cpython(self, mock_interpreter_name, monkeypatch):
         if mock_interpreter_name("CPython"):
             monkeypatch.setattr(tags, "_cpython_abis", lambda *a: ["cp33m"])
         if platform.system() != "Linux":
-            monkeypatch.setattr(platform, "system", lambda: "Linux")
+            monkeypatch.setattr(sys, "platform", "linux")
             monkeypatch.setattr(tags, "_linux_platforms", lambda: ["linux_x86_64"])
         abis = list(tags._cpython_abis(sys.version_info[:2]))
         platforms = list(tags._linux_platforms())