waf/waflib/Tools/python.py

#!/usr/bin/env python
# encoding: utf-8
# Thomas Nagy, 2007-2015 (ita)
# Gustavo Carneiro (gjc), 2007

"""
Support for Python, detect the headers and libraries and provide
*use* variables to link C/C++ programs against them::

	def options(opt):
		opt.load('compiler_c python')
	def configure(conf):
		conf.load('compiler_c python')
		conf.check_python_version((2,4,2))
		conf.check_python_headers()
	def build(bld):
		bld.program(features='pyembed', source='a.c', target='myprog')
		bld.shlib(features='pyext', source='b.c', target='mylib')
"""

import os, sys
from waflib import Errors, Logs, Node, Options, Task, Utils
from waflib.TaskGen import extension, before_method, after_method, feature
from waflib.Configure import conf

FRAG = '''
#include <Python.h>
#ifdef __cplusplus
extern "C" {
#endif
	void Py_Initialize(void);
	void Py_Finalize(void);
#ifdef __cplusplus
}
#endif
int main(int argc, char **argv)
{
   (void)argc; (void)argv;
   Py_Initialize();
   Py_Finalize();
   return 0;
}
'''
"""
Piece of C/C++ code used in :py:func:`waflib.Tools.python.check_python_headers`
"""

INST = '''
import sys, py_compile
py_compile.compile(sys.argv[1], sys.argv[2], sys.argv[3], True)
'''
"""
Piece of Python code used in :py:class:`waflib.Tools.python.pyo` and :py:class:`waflib.Tools.python.pyc` for byte-compiling python files
"""

@before_method('process_source')
@feature('py')
def feature_py(self):
	"""
	Create tasks to byte-compile .py files and install them, if requested
	"""
	self.install_path = getattr(self, 'install_path', '${PYTHONDIR}')
	install_from = getattr(self, 'install_from', None)
	if install_from and not isinstance(install_from, Node.Node):
		install_from = self.path.find_dir(install_from)
	self.install_from = install_from

	ver = self.env.PYTHON_VERSION
	if not ver:
		self.bld.fatal('Installing python files requires PYTHON_VERSION, try conf.check_python_version')

	if int(ver.replace('.', '')) > 31:
		self.install_32 = True

@extension('.py')
def process_py(self, node):
	"""
	Add signature of .py file, so it will be byte-compiled when necessary
	"""
	assert(hasattr(self, 'install_path')), 'add features="py" for target "%s" in "%s/wscript".' % (self.target, self.path.abspath())
	self.install_from = getattr(self, 'install_from', None)
	relative_trick = getattr(self, 'relative_trick', True)
	if self.install_from:
		assert isinstance(self.install_from, Node.Node), \
		'add features="py" for target "%s" in "%s/wscript" (%s).' % (self.target, self.path.abspath(), type(self.install_from))

	# where to install the python file
	if self.install_path:
		if self.install_from:
			self.add_install_files(install_to=self.install_path, install_from=node, cwd=self.install_from, relative_trick=relative_trick)
		else:
			self.add_install_files(install_to=self.install_path, install_from=node, relative_trick=relative_trick)

	lst = []
	if self.env.PYC:
		lst.append('pyc')
	if self.env.PYO:
		lst.append('pyo')

	if self.install_path:
		if self.install_from:
			target_dir = node.path_from(self.install_from) if relative_trick else node.name
			pyd = Utils.subst_vars("%s/%s" % (self.install_path, target_dir), self.env)
		else:
			target_dir = node.path_from(self.path) if relative_trick else node.name
			pyd = Utils.subst_vars("%s/%s" % (self.install_path, target_dir), self.env)
	else:
		pyd = node.abspath()

	for ext in lst:
		if self.env.PYTAG and not self.env.NOPYCACHE:
			# __pycache__ installation for python 3.2 - PEP 3147
			name = node.name[:-3]
			pyobj = node.parent.get_bld().make_node('__pycache__').make_node("%s.%s.%s" % (name, self.env.PYTAG, ext))
			pyobj.parent.mkdir()
		else:
			pyobj = node.change_ext(".%s" % ext)

		tsk = self.create_task(ext, node, pyobj)
		tsk.pyd = pyd

		if self.install_path:
			self.add_install_files(install_to=os.path.dirname(pyd), install_from=pyobj, cwd=node.parent.get_bld(), relative_trick=relative_trick)

class pyc(Task.Task):
	"""
	Byte-compiling python files
	"""
	color = 'PINK'
	def __str__(self):
		node = self.outputs[0]
		return node.path_from(node.ctx.launch_node())
	def run(self):
		cmd = [Utils.subst_vars('${PYTHON}', self.env), '-c', INST, self.inputs[0].abspath(), self.outputs[0].abspath(), self.pyd]
		ret = self.generator.bld.exec_command(cmd)
		return ret

class pyo(Task.Task):
	"""
	Byte-compiling python files
	"""
	color = 'PINK'
	def __str__(self):
		node = self.outputs[0]
		return node.path_from(node.ctx.launch_node())
	def run(self):
		cmd = [Utils.subst_vars('${PYTHON}', self.env), Utils.subst_vars('${PYFLAGS_OPT}', self.env), '-c', INST, self.inputs[0].abspath(), self.outputs[0].abspath(), self.pyd]
		ret = self.generator.bld.exec_command(cmd)
		return ret

@feature('pyext')
@before_method('propagate_uselib_vars', 'apply_link')
@after_method('apply_bundle')
def init_pyext(self):
	"""
	Change the values of *cshlib_PATTERN* and *cxxshlib_PATTERN* to remove the
	*lib* prefix from library names.
	"""
	self.uselib = self.to_list(getattr(self, 'uselib', []))
	if not 'PYEXT' in self.uselib:
		self.uselib.append('PYEXT')
	# override shlib_PATTERN set by the osx module
	self.env.cshlib_PATTERN = self.env.cxxshlib_PATTERN = self.env.macbundle_PATTERN = self.env.pyext_PATTERN
	self.env.fcshlib_PATTERN = self.env.dshlib_PATTERN = self.env.pyext_PATTERN

	try:
		if not self.install_path:
			return
	except AttributeError:
		self.install_path = '${PYTHONARCHDIR}'

@feature('pyext')
@before_method('apply_link', 'apply_bundle')
def set_bundle(self):
	"""Mac-specific pyext extension that enables bundles from c_osx.py"""
	if Utils.unversioned_sys_platform() == 'darwin':
		self.mac_bundle = True

@before_method('propagate_uselib_vars')
@feature('pyembed')
def init_pyembed(self):
	"""
	Add the PYEMBED variable.
	"""
	self.uselib = self.to_list(getattr(self, 'uselib', []))
	if not 'PYEMBED' in self.uselib:
		self.uselib.append('PYEMBED')

@conf
def get_sysconfig_variable(self, variable):
	"""
	Spawn a new python process to dump configuration variables

	:param variable: variable to print
	:type variable: string
	:return: the variable value
	:rtype: string
	"""

	env = dict(os.environ)
	try:
		del env['MACOSX_DEPLOYMENT_TARGET'] # see comments in the OSX tool
	except KeyError:
		pass

	cmd = self.env.PYTHON + ["-c", "import sysconfig; print(sysconfig.get_config_var('{}'))".format(variable)]
	out = self.cmd_and_log(cmd, env=env).strip()

	if out == "None":
		return ""
	else:
		return out

@conf
def get_sysconfig_variables(self, variables):
	"""
	Spawn a new python process to dump configuration variables

	:param variables: variables to print
	:type variables: list of string
	:return: the variable values
	:rtype: list of string
	"""
	return [self.get_sysconfig_variable(variable=v) for v in variables]

@conf
def get_sysconfig_path(self, name):
	"""
	Spawn a new python process to dump configuration paths

	:param name: path to print
	:type variable: string
	:return: the path value
	:rtype: string
	"""

	env = dict(os.environ)
	try:
		del env['MACOSX_DEPLOYMENT_TARGET'] # see comments in the OSX tool
	except KeyError:
		pass

	cmd = self.env.PYTHON + ["-c", "import sysconfig; print(sysconfig.get_path('{}'))".format(name)]
	out = self.cmd_and_log(cmd, env=env).strip()

	if out == "None":
		return ""
	else:
		return out

@conf
def test_pyembed(self, mode, msg='Testing pyembed configuration'):
	self.check(header_name='Python.h', define_name='HAVE_PYEMBED', msg=msg,
		fragment=FRAG, errmsg='Could not build a python embedded interpreter',
		features='%s %sprogram pyembed' % (mode, mode))

@conf
def test_pyext(self, mode, msg='Testing pyext configuration'):
	self.check(header_name='Python.h', define_name='HAVE_PYEXT', msg=msg,
		fragment=FRAG, errmsg='Could not build python extensions',
		features='%s %sshlib pyext' % (mode, mode))

@conf
def python_cross_compile(self, features='pyembed pyext'):
	"""
	For cross-compilation purposes, it is possible to bypass the normal detection and set the flags that you want:
	PYTHON_VERSION='3.4' PYTAG='cpython34' pyext_PATTERN="%s.so" PYTHON_LDFLAGS='-lpthread -ldl' waf configure

	The following variables are used:
	PYTHON_VERSION    required
	PYTAG             required
	PYTHON_LDFLAGS    required
	pyext_PATTERN     required
	PYTHON_PYEXT_LDFLAGS
	PYTHON_PYEMBED_LDFLAGS
	"""
	features = Utils.to_list(features)
	if not ('PYTHON_LDFLAGS' in self.environ or 'PYTHON_PYEXT_LDFLAGS' in self.environ or 'PYTHON_PYEMBED_LDFLAGS' in self.environ):
		return False

	for x in 'PYTHON_VERSION PYTAG pyext_PATTERN'.split():
		if not x in self.environ:
			self.fatal('Please set %s in the os environment' % x)
		else:
			self.env[x] = self.environ[x]

	xx = self.env.CXX_NAME and 'cxx' or 'c'
	if 'pyext' in features:
		flags = self.environ.get('PYTHON_PYEXT_LDFLAGS', self.environ.get('PYTHON_LDFLAGS'))
		if flags is None:
			self.fatal('No flags provided through PYTHON_PYEXT_LDFLAGS as required')
		else:
			self.parse_flags(flags, 'PYEXT')
		self.test_pyext(xx)
	if 'pyembed' in features:
		flags = self.environ.get('PYTHON_PYEMBED_LDFLAGS', self.environ.get('PYTHON_LDFLAGS'))
		if flags is None:
			self.fatal('No flags provided through PYTHON_PYEMBED_LDFLAGS as required')
		else:
			self.parse_flags(flags, 'PYEMBED')
		self.test_pyembed(xx)
	return True

@conf
def check_python_headers(conf, features='pyembed pyext'):
	"""
	Check for headers and libraries necessary to extend or embed python by using the module *sysconfig*.
	On success the environment variables xxx_PYEXT and xxx_PYEMBED are added:

	* PYEXT: for compiling python extensions
	* PYEMBED: for embedding a python interpreter
	"""
	features = Utils.to_list(features)
	assert ('pyembed' in features) or ('pyext' in features), "check_python_headers features must include 'pyembed' and/or 'pyext'"
	env = conf.env
	if not env.CC_NAME and not env.CXX_NAME:
		conf.fatal('load a compiler first (gcc, g++, ..)')

	# bypass all the code below for cross-compilation
	if conf.python_cross_compile(features):
		return

	if not env.PYTHON_VERSION:
		conf.check_python_version()

	pybin = env.PYTHON
	if not pybin:
		conf.fatal('Could not find the python executable')

	# so we actually do all this for compatibility reasons and for obtaining pyext_PATTERN below
	v = 'prefix SO EXT_SUFFIX LDFLAGS LIBDIR LIBPL INCLUDEPY Py_ENABLE_SHARED MACOSX_DEPLOYMENT_TARGET LDSHARED CFLAGS LDVERSION'.split()
	try:
		lst = conf.get_sysconfig_variables(variables=v)
	except RuntimeError:
		conf.fatal("Python development headers not found (-v for details).")

	vals = ['%s = %r' % (x, y) for (x, y) in zip(v, lst)]
	conf.to_log("Configuration returned from %r:\n%s\n" % (pybin, '\n'.join(vals)))

	dct = dict(zip(v, lst))
	x = 'MACOSX_DEPLOYMENT_TARGET'
	if dct[x]:
		env[x] = conf.environ[x] = str(dct[x])
	env.pyext_PATTERN = '%s' + (dct['EXT_SUFFIX'] or dct['SO']) # SO is deprecated in 3.5 and removed in 3.11


	# Try to get pythonX.Y-config
	num = '.'.join(env.PYTHON_VERSION.split('.')[:2])
	conf.find_program([''.join(pybin) + '-config', 'python%s-config' % num, 'python-config-%s' % num, 'python%sm-config' % num], var='PYTHON_CONFIG', msg="python-config", mandatory=False)

	if env.PYTHON_CONFIG:
		# check python-config output only once
		if conf.env.HAVE_PYTHON_H:
			return

		# python2.6-config requires 3 runs
		all_flags = [['--cflags', '--libs', '--ldflags']]
		if sys.hexversion < 0x2070000:
			all_flags = [[k] for k in all_flags[0]]

		xx = env.CXX_NAME and 'cxx' or 'c'

		if 'pyembed' in features:
			for flags in all_flags:
				# Python 3.8 has different flags for pyembed, needs --embed
				embedflags = flags + ['--embed']
				try:
					conf.check_cfg(msg='Asking python-config for pyembed %r flags' % ' '.join(embedflags), path=env.PYTHON_CONFIG, package='', uselib_store='PYEMBED', args=embedflags)
				except conf.errors.ConfigurationError:
					# However Python < 3.8 doesn't accept --embed, so we need a fallback
					conf.check_cfg(msg='Asking python-config for pyembed %r flags' % ' '.join(flags), path=env.PYTHON_CONFIG, package='', uselib_store='PYEMBED', args=flags)

			try:
				conf.test_pyembed(xx)
			except conf.errors.ConfigurationError:
				# python bug 7352
				if dct['Py_ENABLE_SHARED'] and dct['LIBDIR']:
					env.append_unique('LIBPATH_PYEMBED', [dct['LIBDIR']])
					conf.test_pyembed(xx)
				else:
					raise

		if 'pyext' in features:
			for flags in all_flags:
				conf.check_cfg(msg='Asking python-config for pyext %r flags' % ' '.join(flags), path=env.PYTHON_CONFIG, package='', uselib_store='PYEXT', args=flags)

			try:
				conf.test_pyext(xx)
			except conf.errors.ConfigurationError:
				# python bug 7352
				if dct['Py_ENABLE_SHARED'] and dct['LIBDIR']:
					env.append_unique('LIBPATH_PYEXT', [dct['LIBDIR']])
					conf.test_pyext(xx)
				else:
					raise

		conf.define('HAVE_PYTHON_H', 1)
		return

	# No python-config, do something else on windows systems
	all_flags = dct['LDFLAGS'] + ' ' + dct['CFLAGS']
	conf.parse_flags(all_flags, 'PYEMBED')

	all_flags = dct['LDFLAGS'] + ' ' + dct['LDSHARED'] + ' ' + dct['CFLAGS']
	conf.parse_flags(all_flags, 'PYEXT')

	result = None
	if not dct["LDVERSION"]:
		dct["LDVERSION"] = env.PYTHON_VERSION

	# further simplification will be complicated
	for name in ('python' + dct['LDVERSION'], 'python' + env.PYTHON_VERSION + 'm', 'python' + env.PYTHON_VERSION.replace('.', '')):

		# LIBPATH_PYEMBED is already set; see if it works.
		if not result and env.LIBPATH_PYEMBED:
			path = env.LIBPATH_PYEMBED
			conf.to_log("\n\n# Trying default LIBPATH_PYEMBED: %r\n" % path)
			result = conf.check(lib=name, uselib='PYEMBED', libpath=path, mandatory=False, msg='Checking for library %s in LIBPATH_PYEMBED' % name)

		if not result and dct['LIBDIR']:
			path = [dct['LIBDIR']]
			conf.to_log("\n\n# try again with -L$python_LIBDIR: %r\n" % path)
			result = conf.check(lib=name, uselib='PYEMBED', libpath=path, mandatory=False, msg='Checking for library %s in LIBDIR' % name)

		if not result and dct['LIBPL']:
			path = [dct['LIBPL']]
			conf.to_log("\n\n# try again with -L$python_LIBPL (some systems don't install the python library in $prefix/lib)\n")
			result = conf.check(lib=name, uselib='PYEMBED', libpath=path, mandatory=False, msg='Checking for library %s in python_LIBPL' % name)

		if not result:
			path = [os.path.join(dct['prefix'], "libs")]
			conf.to_log("\n\n# try again with -L$prefix/libs, and pythonXY rather than pythonX.Y (win32)\n")
			result = conf.check(lib=name, uselib='PYEMBED', libpath=path, mandatory=False, msg='Checking for library %s in $prefix/libs' % name)

		if not result:
			path = [os.path.normpath(os.path.join(dct['INCLUDEPY'], '..', 'libs'))]
			conf.to_log("\n\n# try again with -L$INCLUDEPY/../libs, and pythonXY rather than pythonX.Y (win32)\n")
			result = conf.check(lib=name, uselib='PYEMBED', libpath=path, mandatory=False, msg='Checking for library %s in $INCLUDEPY/../libs' % name)

		if result:
			break # do not forget to set LIBPATH_PYEMBED

	if result:
		env.LIBPATH_PYEMBED = path
		env.append_value('LIB_PYEMBED', [name])
	else:
		conf.to_log("\n\n### LIB NOT FOUND\n")

	# under certain conditions, python extensions must link to
	# python libraries, not just python embedding programs.
	if Utils.is_win32 or dct['Py_ENABLE_SHARED']:
		env.LIBPATH_PYEXT = env.LIBPATH_PYEMBED
		env.LIB_PYEXT = env.LIB_PYEMBED

	conf.to_log("Include path for Python extensions (found via sysconfig module): %r\n" % (dct['INCLUDEPY'],))
	env.INCLUDES_PYEXT = [dct['INCLUDEPY']]
	env.INCLUDES_PYEMBED = [dct['INCLUDEPY']]

	# Code using the Python API needs to be compiled with -fno-strict-aliasing
	if env.CC_NAME == 'gcc':
		env.append_unique('CFLAGS_PYEMBED', ['-fno-strict-aliasing'])
		env.append_unique('CFLAGS_PYEXT', ['-fno-strict-aliasing'])
	if env.CXX_NAME == 'gcc':
		env.append_unique('CXXFLAGS_PYEMBED', ['-fno-strict-aliasing'])
		env.append_unique('CXXFLAGS_PYEXT', ['-fno-strict-aliasing'])

	if env.CC_NAME == "msvc":
		# From https://github.com/python/cpython/blob/main/Lib/distutils/msvccompiler.py
		env.append_value('CFLAGS_PYEXT', [ '/nologo', '/Ox', '/MD', '/W3', '/GX', '/DNDEBUG'])
		env.append_value('CXXFLAGS_PYEXT', [ '/nologo', '/Ox', '/MD', '/W3', '/GX', '/DNDEBUG'])
		env.append_value('LINKFLAGS_PYEXT', ['/DLL', '/nologo', '/INCREMENTAL:NO'])

	# See if it compiles
	conf.check(header_name='Python.h', define_name='HAVE_PYTHON_H', uselib='PYEMBED', fragment=FRAG, errmsg='Broken python installation? Get python-config now!')

@conf
def check_python_version(conf, minver=None):
	"""
	Check if the python interpreter is found matching a given minimum version.
	minver should be a tuple, eg. to check for python >= 2.4.2 pass (2,4,2) as minver.

	If successful, PYTHON_VERSION is defined as 'MAJOR.MINOR' (eg. '2.4')
	of the actual python version found, and PYTHONDIR and PYTHONARCHDIR
	are defined, pointing to the site-packages directories appropriate for
	this python version, where modules/packages/extensions should be
	installed.

	:param minver: minimum version
	:type minver: tuple of int
	"""
	assert minver is None or isinstance(minver, tuple)
	pybin = conf.env.PYTHON
	if not pybin:
		conf.fatal('could not find the python executable')

	# Get python version string
	cmd = pybin + ['-c', 'import sys\nfor x in sys.version_info: print(str(x))']
	Logs.debug('python: Running python command %r', cmd)
	lines = conf.cmd_and_log(cmd).split()
	assert len(lines) == 5, "found %r lines, expected 5: %r" % (len(lines), lines)
	pyver_tuple = (int(lines[0]), int(lines[1]), int(lines[2]), lines[3], int(lines[4]))

	# Compare python version with the minimum required
	result = (minver is None) or (pyver_tuple >= minver)

	if result:
		# define useful environment variables
		pyver = '.'.join([str(x) for x in pyver_tuple[:2]])
		conf.env.PYTHON_VERSION = pyver

		if 'PYTHONDIR' in conf.env:
			# Check if --pythondir was specified
			pydir = conf.env.PYTHONDIR
		elif 'PYTHONDIR' in conf.environ:
			# Check environment for PYTHONDIR
			pydir = conf.environ['PYTHONDIR']
		else:
			pydir = conf.get_sysconfig_path('purelib')

		if 'PYTHONARCHDIR' in conf.env:
			# Check if --pythonarchdir was specified
			pyarchdir = conf.env.PYTHONARCHDIR
		elif 'PYTHONARCHDIR' in conf.environ:
			# Check environment for PYTHONDIR
			pyarchdir = conf.environ['PYTHONARCHDIR']
		else:
			# Finally, try to guess
			pyarchdir = conf.get_sysconfig_path('platlib')

			if not pyarchdir:
				pyarchdir = pydir

		if hasattr(conf, 'define'): # conf.define is added by the C tool, so may not exist
			conf.define('PYTHONDIR', pydir)
			conf.define('PYTHONARCHDIR', pyarchdir)

		conf.env.PYTHONDIR = pydir
		conf.env.PYTHONARCHDIR = pyarchdir

	# Feedback
	pyver_full = '.'.join(map(str, pyver_tuple[:3]))
	if minver is None:
		conf.msg('Checking for python version', pyver_full)
	else:
		minver_str = '.'.join(map(str, minver))
		conf.msg('Checking for python version >= %s' % (minver_str,), pyver_full, color=result and 'GREEN' or 'YELLOW')

	if not result:
		conf.fatal('The python version is too old, expecting %r' % (minver,))

PYTHON_MODULE_TEMPLATE = '''
import %s as current_module
version = getattr(current_module, '__version__', None)
if version is not None:
	print(str(version))
else:
	print('unknown version')
'''

@conf
def check_python_module(conf, module_name, condition=''):
	"""
	Check if the selected python interpreter can import the given python module::

		def configure(conf):
			conf.check_python_module('pygccxml')
			conf.check_python_module('re', condition="ver > num(2, 0, 4) and ver <= num(3, 0, 0)")

	:param module_name: module
	:type module_name: string
	"""
	msg = "Checking for python module %r" % module_name
	if condition:
		msg = '%s (%s)' % (msg, condition)
	conf.start_msg(msg)
	try:
		ret = conf.cmd_and_log(conf.env.PYTHON + ['-c', PYTHON_MODULE_TEMPLATE % module_name])
	except Errors.WafError:
		conf.end_msg(False)
		conf.fatal('Could not find the python module %r' % module_name)

	ret = ret.strip()
	if condition:
		conf.end_msg(ret)
		if ret == 'unknown version':
			conf.fatal('Could not check the %s version' % module_name)

		def num(*k):
			if isinstance(k[0], int):
				return Utils.loose_version('.'.join([str(x) for x in k]))
			else:
				return Utils.loose_version(k[0])
		d = {'num': num, 'ver': Utils.loose_version(ret)}
		ev = eval(condition, {}, d)
		if not ev:
			conf.fatal('The %s version does not satisfy the requirements' % module_name)
	else:
		if ret == 'unknown version':
			conf.end_msg(True)
		else:
			conf.end_msg(ret)

def configure(conf):
	"""
	Detect the python interpreter
	"""
	v = conf.env
	if getattr(Options.options, 'pythondir', None):
		v.PYTHONDIR = Options.options.pythondir
	if getattr(Options.options, 'pythonarchdir', None):
		v.PYTHONARCHDIR = Options.options.pythonarchdir
	if getattr(Options.options, 'nopycache', None):
		v.NOPYCACHE=Options.options.nopycache

	if not v.PYTHON:
		v.PYTHON = [getattr(Options.options, 'python', None) or sys.executable]
	v.PYTHON = Utils.to_list(v.PYTHON)
	conf.find_program('python', var='PYTHON')

	v.PYFLAGS = ''
	v.PYFLAGS_OPT = '-O'

	v.PYC = getattr(Options.options, 'pyc', 1)
	v.PYO = getattr(Options.options, 'pyo', 1)

	try:
		v.PYTAG = conf.cmd_and_log(conf.env.PYTHON + ['-c', "import sys\ntry:\n print(sys.implementation.cache_tag)\nexcept AttributeError:\n import imp\n print(imp.get_tag())\n"]).strip()
	except Errors.WafError:
		pass

def options(opt):
	"""
	Add python-specific options
	"""
	pyopt=opt.add_option_group("Python Options")
	pyopt.add_option('--nopyc', dest = 'pyc', action='store_false', default=1,
					 help = 'Do not install bytecode compiled .pyc files (configuration) [Default:install]')
	pyopt.add_option('--nopyo', dest='pyo', action='store_false', default=1,
					 help='Do not install optimised compiled .pyo files (configuration) [Default:install]')
	pyopt.add_option('--nopycache',dest='nopycache', action='store_true',
					 help='Do not use __pycache__ directory to install objects [Default:auto]')
	pyopt.add_option('--python', dest="python",
					 help='python binary to be used [Default: %s]' % sys.executable)
	pyopt.add_option('--pythondir', dest='pythondir',
					 help='Installation path for python modules (py, platform-independent .py and .pyc files)')
	pyopt.add_option('--pythonarchdir', dest='pythonarchdir',
					 help='Installation path for python extension (pyext, platform-dependent .so or .dylib files)')