/usr/lib/python2.7/dist-packages/nibabel/optpkg.py is in python-nibabel 2.1.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 | """ Routines to support optional packages """
from distutils.version import LooseVersion
from .externals.six import string_types, callable
try:
import nose
except ImportError:
have_nose = False
else:
have_nose = True
from .tripwire import TripWire
def _check_pkg_version(pkg, min_version):
# Default version checking function
if isinstance(min_version, string_types):
min_version = LooseVersion(min_version)
try:
return min_version <= pkg.__version__
except AttributeError:
return False
def optional_package(name, trip_msg=None, min_version=None):
""" Return package-like thing and module setup for package `name`
Parameters
----------
name : str
package name
trip_msg : None or str
message to give when someone tries to use the return package, but we
could not import it at an acceptable version, and have returned a
TripWire object instead. Default message if None.
min_version : None or str or LooseVersion or callable
If None, do not specify a minimum version. If str, convert to a
`distutils.version.LooseVersion`. If str or LooseVersion` compare to
version of package `name` with ``min_version <= pkg.__version__``. If
callable, accepts imported ``pkg`` as argument, and returns value of
callable is True for acceptable package versions, False otherwise.
Returns
-------
pkg_like : module or ``TripWire`` instance
If we can import the package, return it. Otherwise return an object
raising an error when accessed
have_pkg : bool
True if import for package was successful, false otherwise
module_setup : function
callable usually set as ``setup_module`` in calling namespace, to allow
skipping tests.
Examples
--------
Typical use would be something like this at the top of a module using an
optional package:
>>> from nibabel.optpkg import optional_package
>>> pkg, have_pkg, setup_module = optional_package('not_a_package')
Of course in this case the package doesn't exist, and so, in the module:
>>> have_pkg
False
and
>>> pkg.some_function() #doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
TripWireError: We need package not_a_package for these functions,
but ``import not_a_package`` raised an ImportError
If the module does exist - we get the module
>>> pkg, _, _ = optional_package('os')
>>> hasattr(pkg, 'path')
True
Or a submodule if that's what we asked for
>>> subpkg, _, _ = optional_package('os.path')
>>> hasattr(subpkg, 'dirname')
True
"""
if callable(min_version):
check_version = min_version
elif min_version is None:
check_version = lambda pkg: True
else:
check_version = lambda pkg: _check_pkg_version(pkg, min_version)
# fromlist=[''] results in submodule being returned, rather than the top
# level module. See help(__import__)
fromlist = [''] if '.' in name else []
try:
pkg = __import__(name, fromlist=fromlist)
except ImportError:
pass
else: # import worked
# top level module
if check_version(pkg):
return pkg, True, lambda: None
# Failed version check
if trip_msg is None:
if callable(min_version):
trip_msg = 'Package %s fails version check' % min_version
else:
trip_msg = ('These functions need %s version >= %s' %
(name, min_version))
if trip_msg is None:
trip_msg = ('We need package %s for these functions, but '
'``import %s`` raised an ImportError'
% (name, name))
pkg = TripWire(trip_msg)
def setup_module():
if have_nose:
raise nose.plugins.skip.SkipTest('No %s for these tests'
% name)
return pkg, False, setup_module
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