188 lines
7.5 KiB
Python
188 lines
7.5 KiB
Python
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"""Tools to assist importing optional external modules."""
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import sys
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import re
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# Override these in the module to change the default warning behavior.
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# For example, you might set both to False before running the tests so that
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# warnings are not printed to the console, or set both to True for debugging.
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WARN_NOT_INSTALLED = None # Default is False
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WARN_OLD_VERSION = None # Default is True
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def __sympy_debug():
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# helper function from sympy/__init__.py
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# We don't just import SYMPY_DEBUG from that file because we don't want to
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# import all of SymPy just to use this module.
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import os
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debug_str = os.getenv('SYMPY_DEBUG', 'False')
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if debug_str in ('True', 'False'):
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return eval(debug_str)
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else:
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raise RuntimeError("unrecognized value for SYMPY_DEBUG: %s" %
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debug_str)
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if __sympy_debug():
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WARN_OLD_VERSION = True
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WARN_NOT_INSTALLED = True
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_component_re = re.compile(r'(\d+ | [a-z]+ | \.)', re.VERBOSE)
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def version_tuple(vstring):
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# Parse a version string to a tuple e.g. '1.2' -> (1, 2)
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# Simplified from distutils.version.LooseVersion which was deprecated in
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# Python 3.10.
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components = []
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for x in _component_re.split(vstring):
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if x and x != '.':
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try:
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x = int(x)
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except ValueError:
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pass
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components.append(x)
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return tuple(components)
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def import_module(module, min_module_version=None, min_python_version=None,
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warn_not_installed=None, warn_old_version=None,
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module_version_attr='__version__', module_version_attr_call_args=None,
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import_kwargs={}, catch=()):
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"""
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Import and return a module if it is installed.
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If the module is not installed, it returns None.
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A minimum version for the module can be given as the keyword argument
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min_module_version. This should be comparable against the module version.
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By default, module.__version__ is used to get the module version. To
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override this, set the module_version_attr keyword argument. If the
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attribute of the module to get the version should be called (e.g.,
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module.version()), then set module_version_attr_call_args to the args such
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that module.module_version_attr(*module_version_attr_call_args) returns the
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module's version.
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If the module version is less than min_module_version using the Python <
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comparison, None will be returned, even if the module is installed. You can
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use this to keep from importing an incompatible older version of a module.
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You can also specify a minimum Python version by using the
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min_python_version keyword argument. This should be comparable against
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sys.version_info.
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If the keyword argument warn_not_installed is set to True, the function will
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emit a UserWarning when the module is not installed.
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If the keyword argument warn_old_version is set to True, the function will
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emit a UserWarning when the library is installed, but cannot be imported
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because of the min_module_version or min_python_version options.
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Note that because of the way warnings are handled, a warning will be
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emitted for each module only once. You can change the default warning
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behavior by overriding the values of WARN_NOT_INSTALLED and WARN_OLD_VERSION
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in sympy.external.importtools. By default, WARN_NOT_INSTALLED is False and
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WARN_OLD_VERSION is True.
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This function uses __import__() to import the module. To pass additional
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options to __import__(), use the import_kwargs keyword argument. For
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example, to import a submodule A.B, you must pass a nonempty fromlist option
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to __import__. See the docstring of __import__().
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This catches ImportError to determine if the module is not installed. To
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catch additional errors, pass them as a tuple to the catch keyword
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argument.
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Examples
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========
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>>> from sympy.external import import_module
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>>> numpy = import_module('numpy')
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>>> numpy = import_module('numpy', min_python_version=(2, 7),
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... warn_old_version=False)
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>>> numpy = import_module('numpy', min_module_version='1.5',
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... warn_old_version=False) # numpy.__version__ is a string
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>>> # gmpy does not have __version__, but it does have gmpy.version()
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>>> gmpy = import_module('gmpy', min_module_version='1.14',
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... module_version_attr='version', module_version_attr_call_args=(),
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... warn_old_version=False)
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>>> # To import a submodule, you must pass a nonempty fromlist to
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>>> # __import__(). The values do not matter.
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>>> p3 = import_module('mpl_toolkits.mplot3d',
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... import_kwargs={'fromlist':['something']})
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>>> # matplotlib.pyplot can raise RuntimeError when the display cannot be opened
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>>> matplotlib = import_module('matplotlib',
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... import_kwargs={'fromlist':['pyplot']}, catch=(RuntimeError,))
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"""
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# keyword argument overrides default, and global variable overrides
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# keyword argument.
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warn_old_version = (WARN_OLD_VERSION if WARN_OLD_VERSION is not None
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else warn_old_version or True)
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warn_not_installed = (WARN_NOT_INSTALLED if WARN_NOT_INSTALLED is not None
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else warn_not_installed or False)
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import warnings
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# Check Python first so we don't waste time importing a module we can't use
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if min_python_version:
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if sys.version_info < min_python_version:
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if warn_old_version:
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warnings.warn("Python version is too old to use %s "
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"(%s or newer required)" % (
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module, '.'.join(map(str, min_python_version))),
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UserWarning, stacklevel=2)
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return
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try:
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mod = __import__(module, **import_kwargs)
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## there's something funny about imports with matplotlib and py3k. doing
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## from matplotlib import collections
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## gives python's stdlib collections module. explicitly re-importing
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## the module fixes this.
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from_list = import_kwargs.get('fromlist', ())
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for submod in from_list:
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if submod == 'collections' and mod.__name__ == 'matplotlib':
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__import__(module + '.' + submod)
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except ImportError:
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if warn_not_installed:
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warnings.warn("%s module is not installed" % module, UserWarning,
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stacklevel=2)
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return
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except catch as e:
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if warn_not_installed:
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warnings.warn(
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"%s module could not be used (%s)" % (module, repr(e)),
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stacklevel=2)
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return
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if min_module_version:
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modversion = getattr(mod, module_version_attr)
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if module_version_attr_call_args is not None:
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modversion = modversion(*module_version_attr_call_args)
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if version_tuple(modversion) < version_tuple(min_module_version):
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if warn_old_version:
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# Attempt to create a pretty string version of the version
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if isinstance(min_module_version, str):
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verstr = min_module_version
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elif isinstance(min_module_version, (tuple, list)):
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verstr = '.'.join(map(str, min_module_version))
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else:
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# Either don't know what this is. Hopefully
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# it's something that has a nice str version, like an int.
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verstr = str(min_module_version)
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warnings.warn("%s version is too old to use "
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"(%s or newer required)" % (module, verstr),
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UserWarning, stacklevel=2)
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return
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return mod
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