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
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
|
:mod:`pkgutil` --- Package extension utility
============================================
.. module:: pkgutil
:synopsis: Utilities for the import system.
**Source code:** :source:`Lib/pkgutil.py`
--------------
This module provides utilities for the import system, in particular package
support.
.. class:: ModuleInfo(module_finder, name, ispkg)
A namedtuple that holds a brief summary of a module's info.
.. versionadded:: 3.6
.. function:: extend_path(path, name)
Extend the search path for the modules which comprise a package. Intended
use is to place the following code in a package's :file:`__init__.py`::
from pkgutil import extend_path
__path__ = extend_path(__path__, __name__)
This will add to the package's ``__path__`` all subdirectories of directories
on ``sys.path`` named after the package. This is useful if one wants to
distribute different parts of a single logical package as multiple
directories.
It also looks for :file:`\*.pkg` files beginning where ``*`` matches the
*name* argument. This feature is similar to :file:`\*.pth` files (see the
:mod:`site` module for more information), except that it doesn't special-case
lines starting with ``import``. A :file:`\*.pkg` file is trusted at face
value: apart from checking for duplicates, all entries found in a
:file:`\*.pkg` file are added to the path, regardless of whether they exist
on the filesystem. (This is a feature.)
If the input path is not a list (as is the case for frozen packages) it is
returned unchanged. The input path is not modified; an extended copy is
returned. Items are only appended to the copy at the end.
It is assumed that :data:`sys.path` is a sequence. Items of :data:`sys.path`
that are not strings referring to existing directories are ignored. Unicode
items on :data:`sys.path` that cause errors when used as filenames may cause
this function to raise an exception (in line with :func:`os.path.isdir`
behavior).
.. class:: ImpImporter(dirname=None)
:pep:`302` Finder that wraps Python's "classic" import algorithm.
If *dirname* is a string, a :pep:`302` finder is created that searches that
directory. If *dirname* is ``None``, a :pep:`302` finder is created that
searches the current :data:`sys.path`, plus any modules that are frozen or
built-in.
Note that :class:`ImpImporter` does not currently support being used by
placement on :data:`sys.meta_path`.
.. deprecated:: 3.3
This emulation is no longer needed, as the standard import mechanism
is now fully PEP 302 compliant and available in :mod:`importlib`.
.. class:: ImpLoader(fullname, file, filename, etc)
:term:`Loader` that wraps Python's "classic" import algorithm.
.. deprecated:: 3.3
This emulation is no longer needed, as the standard import mechanism
is now fully PEP 302 compliant and available in :mod:`importlib`.
.. function:: find_loader(fullname)
Retrieve a module :term:`loader` for the given *fullname*.
This is a backwards compatibility wrapper around
:func:`importlib.util.find_spec` that converts most failures to
:exc:`ImportError` and only returns the loader rather than the full
:class:`ModuleSpec`.
.. versionchanged:: 3.3
Updated to be based directly on :mod:`importlib` rather than relying
on the package internal PEP 302 import emulation.
.. versionchanged:: 3.4
Updated to be based on :pep:`451`
.. function:: get_importer(path_item)
Retrieve a :term:`finder` for the given *path_item*.
The returned finder is cached in :data:`sys.path_importer_cache` if it was
newly created by a path hook.
The cache (or part of it) can be cleared manually if a rescan of
:data:`sys.path_hooks` is necessary.
.. versionchanged:: 3.3
Updated to be based directly on :mod:`importlib` rather than relying
on the package internal PEP 302 import emulation.
.. function:: get_loader(module_or_name)
Get a :term:`loader` object for *module_or_name*.
If the module or package is accessible via the normal import mechanism, a
wrapper around the relevant part of that machinery is returned. Returns
``None`` if the module cannot be found or imported. If the named module is
not already imported, its containing package (if any) is imported, in order
to establish the package ``__path__``.
.. versionchanged:: 3.3
Updated to be based directly on :mod:`importlib` rather than relying
on the package internal PEP 302 import emulation.
.. versionchanged:: 3.4
Updated to be based on :pep:`451`
.. function:: iter_importers(fullname='')
Yield :term:`finder` objects for the given module name.
If fullname contains a '.', the finders will be for the package
containing fullname, otherwise they will be all registered top level
finders (i.e. those on both sys.meta_path and sys.path_hooks).
If the named module is in a package, that package is imported as a side
effect of invoking this function.
If no module name is specified, all top level finders are produced.
.. versionchanged:: 3.3
Updated to be based directly on :mod:`importlib` rather than relying
on the package internal PEP 302 import emulation.
.. function:: iter_modules(path=None, prefix='')
Yields :class:`ModuleInfo` for all submodules on *path*, or, if
*path* is ``None``, all top-level modules on ``sys.path``.
*path* should be either ``None`` or a list of paths to look for modules in.
*prefix* is a string to output on the front of every module name on output.
.. note::
Only works for a :term:`finder` which defines an ``iter_modules()``
method. This interface is non-standard, so the module also provides
implementations for :class:`importlib.machinery.FileFinder` and
:class:`zipimport.zipimporter`.
.. versionchanged:: 3.3
Updated to be based directly on :mod:`importlib` rather than relying
on the package internal PEP 302 import emulation.
.. function:: walk_packages(path=None, prefix='', onerror=None)
Yields :class:`ModuleInfo` for all modules recursively on
*path*, or, if *path* is ``None``, all accessible modules.
*path* should be either ``None`` or a list of paths to look for modules in.
*prefix* is a string to output on the front of every module name on output.
Note that this function must import all *packages* (*not* all modules!) on
the given *path*, in order to access the ``__path__`` attribute to find
submodules.
*onerror* is a function which gets called with one argument (the name of the
package which was being imported) if any exception occurs while trying to
import a package. If no *onerror* function is supplied, :exc:`ImportError`\s
are caught and ignored, while all other exceptions are propagated,
terminating the search.
Examples::
# list all modules python can access
walk_packages()
# list all submodules of ctypes
walk_packages(ctypes.__path__, ctypes.__name__ + '.')
.. note::
Only works for a :term:`finder` which defines an ``iter_modules()``
method. This interface is non-standard, so the module also provides
implementations for :class:`importlib.machinery.FileFinder` and
:class:`zipimport.zipimporter`.
.. versionchanged:: 3.3
Updated to be based directly on :mod:`importlib` rather than relying
on the package internal PEP 302 import emulation.
.. function:: get_data(package, resource)
Get a resource from a package.
This is a wrapper for the :term:`loader`
:meth:`get_data <importlib.abc.ResourceLoader.get_data>` API. The
*package* argument should be the name of a package, in standard module format
(``foo.bar``). The *resource* argument should be in the form of a relative
filename, using ``/`` as the path separator. The parent directory name
``..`` is not allowed, and nor is a rooted name (starting with a ``/``).
The function returns a binary string that is the contents of the specified
resource.
For packages located in the filesystem, which have already been imported,
this is the rough equivalent of::
d = os.path.dirname(sys.modules[package].__file__)
data = open(os.path.join(d, resource), 'rb').read()
If the package cannot be located or loaded, or it uses a :term:`loader`
which does not support :meth:`get_data <importlib.abc.ResourceLoader.get_data>`,
then ``None`` is returned. In particular, the :term:`loader` for
:term:`namespace packages <namespace package>` does not support
:meth:`get_data <importlib.abc.ResourceLoader.get_data>`.
|
