[Python-checkins] bpo-43312: Functions returning default and preferred sysconfig schemes (GH-24644)

Tue Apr 27 04:46:05 EDT 2021

https://github.com/python/cpython/commit/d92513390a1a0da781bb08c284136f4d7abea36d
commit: d92513390a1a0da781bb08c284136f4d7abea36d
branch: master
author: Tzu-ping Chung <uranusjr at gmail.com>
committer: pfmoore <p.f.moore at gmail.com>
date: 2021年04月27日T09:45:55+01:00
summary:
bpo-43312: Functions returning default and preferred sysconfig schemes (GH-24644)
files:
A Misc/NEWS.d/next/Library/2021-02-25-14-43-59.bpo-43312.6dg9_2.rst
M Doc/library/sysconfig.rst
M Lib/sysconfig.py
M Lib/test/test_sysconfig.py

diff --git a/Doc/library/sysconfig.rst b/Doc/library/sysconfig.rst
index d4463f39fda24..bb8e2d88c0fc9 100644
--- a/Doc/library/sysconfig.rst
+++ b/Doc/library/sysconfig.rst
@@ -107,6 +107,43 @@ identifier. Python currently uses eight paths:
 :mod:`sysconfig`.
 
 
+.. function:: get_default_scheme()
+
+ Return the default scheme name for the current platform.
+
+ .. versionchanged:: 3.10
+ This function was previously named ``_get_default_scheme()`` and
+ considered an implementation detail.
+
+
+.. function:: get_preferred_scheme(key)
+
+ Return a preferred scheme name for an installation layout specified by *key*.
+
+ *key* must be either ``"prefix"``, ``"home"``, or ``"user"``.
+
+ The return value is a scheme name listed in :func:`get_scheme_names`. It
+ can be passed to :mod:`sysconfig` functions that take a *scheme* argument,
+ such as :func:`get_paths`.
+
+ .. versionadded:: 3.10
+
+
+.. function:: _get_preferred_schemes()
+
+ Return a dict containing preferred scheme names on the current platform.
+ Python implementers and redistributors may add their preferred schemes to
+ the ``_INSTALL_SCHEMES`` module-level global value, and modify this function
+ to return those scheme names, to e.g. provide different schemes for system
+ and language package managers to use, so packages installed by either do not
+ mix with those by the other.
+
+ End users should not use this function, but :func:`get_default_scheme` and
+ :func:`get_preferred_scheme()` instead.
+
+ .. versionadded:: 3.10
+
+
 .. function:: get_path_names()
 
 Return a tuple containing all path names currently supported in
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 0e0decd42716e..e8869af0b5cc9 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -79,7 +79,7 @@ def joinuser(*args):
 
 if sys.platform == "darwin" and sys._framework:
 return joinuser("~", "Library", sys._framework,
- "%d.%d" % sys.version_info[:2])
+ f"{sys.version_info[0]}.{sys.version_info[1]}")
 
 return joinuser("~", ".local")
 
@@ -121,8 +121,8 @@ def joinuser(*args):
 'scripts', 'data')
 
 _PY_VERSION = sys.version.split()[0]
-_PY_VERSION_SHORT = '%d.%d' % sys.version_info[:2]
-_PY_VERSION_SHORT_NO_DOT = '%d%d' % sys.version_info[:2]
+_PY_VERSION_SHORT = f'{sys.version_info[0]}.{sys.version_info[1]}'
+_PY_VERSION_SHORT_NO_DOT = f'{sys.version_info[0]}{sys.version_info[1]}'
 _PREFIX = os.path.normpath(sys.prefix)
 _BASE_PREFIX = os.path.normpath(sys.base_prefix)
 _EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
@@ -189,7 +189,7 @@ def _subst_vars(s, local_vars):
 try:
 return s.format(**os.environ)
 except KeyError:
- raise AttributeError('{%s}' % var) from None
+ raise AttributeError(f'{var}') from None
 
 def _extend_dict(target_dict, other_dict):
 target_keys = target_dict.keys()
@@ -212,13 +212,38 @@ def _expand_vars(scheme, vars):
 return res
 
 
-def _get_default_scheme():
- if os.name == 'posix':
- # the default scheme for posix is posix_prefix
- return 'posix_prefix'
- return os.name
+def _get_preferred_schemes():
+ if os.name == 'nt':
+ return {
+ 'prefix': 'nt',
+ 'home': 'posix_home',
+ 'user': 'nt_user',
+ }
+ if sys.platform == 'darwin' and sys._framework:
+ return {
+ 'prefix': 'posix_prefix',
+ 'home': 'posix_home',
+ 'user': 'osx_framework_user',
+ }
+ return {
+ 'prefix': 'posix_prefix',
+ 'home': 'posix_home',
+ 'user': 'posix_user',
+ }
+
+
+def get_preferred_scheme(key):
+ scheme = _get_preferred_schemes()[key]
+ if scheme not in _INSTALL_SCHEMES:
+ raise ValueError(
+ f"{key!r} returned {scheme!r}, which is not a valid scheme "
+ f"on this platform"
+ )
+ return scheme
 
 
+def get_default_scheme():
+ return get_preferred_scheme('prefix')
 
 
 def _parse_makefile(filename, vars=None, keep_unresolved=True):
@@ -354,21 +379,20 @@ def get_makefile_filename():
 if _PYTHON_BUILD:
 return os.path.join(_sys_home or _PROJECT_BASE, "Makefile")
 if hasattr(sys, 'abiflags'):
- config_dir_name = 'config-%s%s' % (_PY_VERSION_SHORT, sys.abiflags)
+ config_dir_name = f'config-{_PY_VERSION_SHORT}{sys.abiflags}'
 else:
 config_dir_name = 'config'
 if hasattr(sys.implementation, '_multiarch'):
- config_dir_name += '-%s' % sys.implementation._multiarch
+ config_dir_name += f'-{sys.implementation._multiarch}'
 return os.path.join(get_path('stdlib'), config_dir_name, 'Makefile')
 
 
 def _get_sysconfigdata_name():
- return os.environ.get('_PYTHON_SYSCONFIGDATA_NAME',
- '_sysconfigdata_{abi}_{platform}_{multiarch}'.format(
- abi=sys.abiflags,
- platform=sys.platform,
- multiarch=getattr(sys.implementation, '_multiarch', ''),
- ))
+ multiarch = getattr(sys.implementation, '_multiarch', '')
+ return os.environ.get(
+ '_PYTHON_SYSCONFIGDATA_NAME',
+ f'_sysconfigdata_{sys.abiflags}_{sys.platform}_{multiarch}',
+ )
 
 
 def _generate_posix_vars():
@@ -380,9 +404,9 @@ def _generate_posix_vars():
 try:
 _parse_makefile(makefile, vars)
 except OSError as e:
- msg = "invalid Python installation: unable to open %s" % makefile
+ msg = f"invalid Python installation: unable to open {makefile}"
 if hasattr(e, "strerror"):
- msg = msg + " (%s)" % e.strerror
+ msg = f"{msg} ({e.strerror})"
 raise OSError(msg)
 # load the installed pyconfig.h:
 config_h = get_config_h_filename()
@@ -390,9 +414,9 @@ def _generate_posix_vars():
 with open(config_h, encoding="utf-8") as f:
 parse_config_h(f, vars)
 except OSError as e:
- msg = "invalid Python installation: unable to open %s" % config_h
+ msg = f"invalid Python installation: unable to open {config_h}"
 if hasattr(e, "strerror"):
- msg = msg + " (%s)" % e.strerror
+ msg = f"{msg} ({e.strerror})"
 raise OSError(msg)
 # On AIX, there are wrong paths to the linker scripts in the Makefile
 # -- these paths are relative to the Python source, but when installed
@@ -418,7 +442,7 @@ def _generate_posix_vars():
 module.build_time_vars = vars
 sys.modules[name] = module
 
- pybuilddir = 'build/lib.%s-%s' % (get_platform(), _PY_VERSION_SHORT)
+ pybuilddir = f'build/lib.{get_platform()}-{_PY_VERSION_SHORT}'
 if hasattr(sys, "gettotalrefcount"):
 pybuilddir += '-pydebug'
 os.makedirs(pybuilddir, exist_ok=True)
@@ -516,7 +540,7 @@ def get_path_names():
 return _SCHEME_KEYS
 
 
-def get_paths(scheme=_get_default_scheme(), vars=None, expand=True):
+def get_paths(scheme=get_default_scheme(), vars=None, expand=True):
 """Return a mapping containing an install scheme.
 
 ``scheme`` is the install scheme name. If not provided, it will
@@ -528,7 +552,7 @@ def get_paths(scheme=_get_default_scheme(), vars=None, expand=True):
 return _INSTALL_SCHEMES[scheme]
 
 
-def get_path(name, scheme=_get_default_scheme(), vars=None, expand=True):
+def get_path(name, scheme=get_default_scheme(), vars=None, expand=True):
 """Return a path corresponding to the scheme.
 
 ``scheme`` is the install scheme name.
@@ -682,16 +706,16 @@ def get_platform():
 # At least on Linux/Intel, 'machine' is the processor --
 # i386, etc.
 # XXX what about Alpha, SPARC, etc?
- return "%s-%s" % (osname, machine)
+ return f"{osname}-{machine}"
 elif osname[:5] == "sunos":
 if release[0] >= "5": # SunOS 5 == Solaris 2
 osname = "solaris"
- release = "%d.%s" % (int(release[0]) - 3, release[2:])
+ release = f"{int(release[0]) - 3}.{release[2:]}"
 # We can't use "platform.architecture()[0]" because a
 # bootstrap problem. We use a dict to get an error
 # if some suspicious happens.
 bitness = {2147483647:"32bit", 9223372036854775807:"64bit"}
- machine += ".%s" % bitness[sys.maxsize]
+ machine += f".{bitness[sys.maxsize]}"
 # fall through to standard osname-release-machine representation
 elif osname[:3] == "aix":
 from _aix_support import aix_platform
@@ -709,7 +733,7 @@ def get_platform():
 get_config_vars(),
 osname, release, machine)
 
- return "%s-%s-%s" % (osname, release, machine)
+ return f"{osname}-{release}-{machine}"
 
 
 def get_python_version():
@@ -745,8 +769,8 @@ def expand_makefile_vars(s, vars):
 def _print_dict(title, data):
 for index, (key, value) in enumerate(sorted(data.items())):
 if index == 0:
- print('%s: ' % (title))
- print('\t%s = "%s"' % (key, value))
+ print(f'{title}: ')
+ print(f'\t{key} = "{value}"')
 
 
 def _main():
@@ -754,9 +778,9 @@ def _main():
 if '--generate-posix-vars' in sys.argv:
 _generate_posix_vars()
 return
- print('Platform: "%s"' % get_platform())
- print('Python version: "%s"' % get_python_version())
- print('Current installation scheme: "%s"' % _get_default_scheme())
+ print(f'Platform: "{get_platform()}"')
+ print(f'Python version: "{get_python_version()}"')
+ print(f'Current installation scheme: "{get_default_scheme()}"')
 print()
 _print_dict('Paths', get_paths())
 print()
diff --git a/Lib/test/test_sysconfig.py b/Lib/test/test_sysconfig.py
index e279957e26ced..b8b9add36d766 100644
--- a/Lib/test/test_sysconfig.py
+++ b/Lib/test/test_sysconfig.py
@@ -14,8 +14,8 @@
 import sysconfig
 from sysconfig import (get_paths, get_platform, get_config_vars,
 get_path, get_path_names, _INSTALL_SCHEMES,
- _get_default_scheme, _expand_vars,
- get_scheme_names, get_config_var, _main)
+ get_default_scheme, get_scheme_names, get_config_var,
+ _expand_vars, _get_preferred_schemes, _main)
 import _osx_support
 
 
@@ -94,17 +94,46 @@ def test_get_path_names(self):
 
 def test_get_paths(self):
 scheme = get_paths()
- default_scheme = _get_default_scheme()
+ default_scheme = get_default_scheme()
 wanted = _expand_vars(default_scheme, None)
 wanted = sorted(wanted.items())
 scheme = sorted(scheme.items())
 self.assertEqual(scheme, wanted)
 
 def test_get_path(self):
- # XXX make real tests here
+ config_vars = get_config_vars()
 for scheme in _INSTALL_SCHEMES:
 for name in _INSTALL_SCHEMES[scheme]:
- res = get_path(name, scheme)
+ expected = _INSTALL_SCHEMES[scheme][name].format(**config_vars)
+ self.assertEqual(
+ os.path.normpath(get_path(name, scheme)),
+ os.path.normpath(expected),
+ )
+
+ def test_get_default_scheme(self):
+ self.assertIn(get_default_scheme(), _INSTALL_SCHEMES)
+
+ def test_get_preferred_schemes(self):
+ expected_schemes = {'prefix', 'home', 'user'}
+
+ # Windows.
+ os.name = 'nt'
+ schemes = _get_preferred_schemes()
+ self.assertIsInstance(schemes, dict)
+ self.assertEqual(set(schemes), expected_schemes)
+
+ # Mac and Linux, shared library build.
+ os.name = 'posix'
+ schemes = _get_preferred_schemes()
+ self.assertIsInstance(schemes, dict)
+ self.assertEqual(set(schemes), expected_schemes)
+
+ # Mac, framework build.
+ os.name = 'posix'
+ sys.platform = 'darwin'
+ sys._framework = True
+ self.assertIsInstance(schemes, dict)
+ self.assertEqual(set(schemes), expected_schemes)
 
 def test_get_config_vars(self):
 cvars = get_config_vars()
diff --git a/Misc/NEWS.d/next/Library/2021-02-25-14-43-59.bpo-43312.6dg9_2.rst b/Misc/NEWS.d/next/Library/2021-02-25-14-43-59.bpo-43312.6dg9_2.rst
new file mode 100644
index 0000000000000..b8def9ceee64c
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-02-25-14-43-59.bpo-43312.6dg9_2.rst
@@ -0,0 +1,3 @@
+New functions :func:`sysconfig.get_preferred_scheme` and
+:func:`sysconfig.get_default_scheme` are added to query a platform for its
+preferred "user", "home", and "prefix" (default) scheme names.
