Brett Cannon | 07fbd78 | 2014-02-06 09:46:08 -0500 | [diff] [blame] | 1 | :mod:`importlib` -- The implementation of :keyword:`import` |
| 2 | =========================================================== |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 3 | |
| 4 | .. module:: importlib |
Brett Cannon | 07fbd78 | 2014-02-06 09:46:08 -0500 | [diff] [blame] | 5 | :synopsis: The implementation of the import machinery. |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 6 | |
| 7 | .. moduleauthor:: Brett Cannon <brett@python.org> |
| 8 | .. sectionauthor:: Brett Cannon <brett@python.org> |
| 9 | |
| 10 | .. versionadded:: 3.1 |
| 11 | |
| 12 | |
| 13 | Introduction |
| 14 | ------------ |
| 15 | |
Brett Cannon | 07fbd78 | 2014-02-06 09:46:08 -0500 | [diff] [blame] | 16 | The purpose of the :mod:`importlib` package is two-fold. One is to provide the |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 17 | implementation of the :keyword:`import` statement (and thus, by extension, the |
| 18 | :func:`__import__` function) in Python source code. This provides an |
Tarek Ziadé | 434caaa | 2009-05-14 12:48:09 +0000 | [diff] [blame] | 19 | implementation of :keyword:`import` which is portable to any Python |
Brett Cannon | 07fbd78 | 2014-02-06 09:46:08 -0500 | [diff] [blame] | 20 | interpreter. This also provides an implementation which is easier to |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 21 | comprehend than one implemented in a programming language other than Python. |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 22 | |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 23 | Two, the components to implement :keyword:`import` are exposed in this |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 24 | package, making it easier for users to create their own custom objects (known |
Brett Cannon | debb98d | 2009-02-16 04:18:01 +0000 | [diff] [blame] | 25 | generically as an :term:`importer`) to participate in the import process. |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 26 | |
| 27 | .. seealso:: |
| 28 | |
| 29 | :ref:`import` |
| 30 | The language reference for the :keyword:`import` statement. |
| 31 | |
Georg Brandl | b7354a6 | 2014-10-29 10:57:37 +0100 | [diff] [blame] | 32 | `Packages specification <http://legacy.python.org/doc/essays/packages.html>`__ |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 33 | Original specification of packages. Some semantics have changed since |
Georg Brandl | 375aec2 | 2011-01-15 17:03:02 +0000 | [diff] [blame] | 34 | the writing of this document (e.g. redirecting based on ``None`` |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 35 | in :data:`sys.modules`). |
| 36 | |
| 37 | The :func:`.__import__` function |
Brett Cannon | 0e13c94 | 2010-06-29 18:26:11 +0000 | [diff] [blame] | 38 | The :keyword:`import` statement is syntactic sugar for this function. |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 39 | |
| 40 | :pep:`235` |
| 41 | Import on Case-Insensitive Platforms |
| 42 | |
| 43 | :pep:`263` |
| 44 | Defining Python Source Code Encodings |
| 45 | |
| 46 | :pep:`302` |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 47 | New Import Hooks |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 48 | |
| 49 | :pep:`328` |
| 50 | Imports: Multi-Line and Absolute/Relative |
| 51 | |
| 52 | :pep:`366` |
| 53 | Main module explicit relative imports |
| 54 | |
Brett Cannon | 07fbd78 | 2014-02-06 09:46:08 -0500 | [diff] [blame] | 55 | :pep:`451` |
| 56 | A ModuleSpec Type for the Import System |
| 57 | |
Nick Coghlan | d5cacbb | 2015-05-23 22:24:10 +1000 | [diff] [blame] | 58 | :pep:`488` |
| 59 | Elimination of PYO files |
| 60 | |
| 61 | :pep:`489` |
| 62 | Multi-phase extension module initialization |
| 63 | |
Brett Cannon | 8917d5e | 2010-01-13 19:21:00 +0000 | [diff] [blame] | 64 | :pep:`3120` |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 65 | Using UTF-8 as the Default Source Encoding |
| 66 | |
Brett Cannon | 30b7a90 | 2010-06-27 21:49:22 +0000 | [diff] [blame] | 67 | :pep:`3147` |
| 68 | PYC Repository Directories |
| 69 | |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 70 | |
| 71 | Functions |
| 72 | --------- |
| 73 | |
Brett Cannon | cb4996a | 2012-08-06 16:34:44 -0400 | [diff] [blame] | 74 | .. function:: __import__(name, globals=None, locals=None, fromlist=(), level=0) |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 75 | |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 76 | An implementation of the built-in :func:`__import__` function. |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 77 | |
Brett Cannon | 3fa8422 | 2015-02-20 10:34:20 -0500 | [diff] [blame] | 78 | .. note:: |
| 79 | Programmatic importing of modules should use :func:`import_module` |
| 80 | instead of this function. |
| 81 | |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 82 | .. function:: import_module(name, package=None) |
| 83 | |
Brett Cannon | 33418c8 | 2009-01-22 18:37:20 +0000 | [diff] [blame] | 84 | Import a module. The *name* argument specifies what module to |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 85 | import in absolute or relative terms |
| 86 | (e.g. either ``pkg.mod`` or ``..mod``). If the name is |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 87 | specified in relative terms, then the *package* argument must be set to |
| 88 | the name of the package which is to act as the anchor for resolving the |
Brett Cannon | afccd63 | 2009-01-20 02:21:27 +0000 | [diff] [blame] | 89 | package name (e.g. ``import_module('..mod', 'pkg.subpkg')`` will import |
Brett Cannon | 2c318a1 | 2009-02-07 01:15:27 +0000 | [diff] [blame] | 90 | ``pkg.mod``). |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 91 | |
Brett Cannon | 2c318a1 | 2009-02-07 01:15:27 +0000 | [diff] [blame] | 92 | The :func:`import_module` function acts as a simplifying wrapper around |
Brett Cannon | 9f4cb1c | 2009-04-01 23:26:47 +0000 | [diff] [blame] | 93 | :func:`importlib.__import__`. This means all semantics of the function are |
Brett Cannon | 3fa8422 | 2015-02-20 10:34:20 -0500 | [diff] [blame] | 94 | derived from :func:`importlib.__import__`. The most important difference |
| 95 | between these two functions is that :func:`import_module` returns the |
| 96 | specified package or module (e.g. ``pkg.mod``), while :func:`__import__` |
| 97 | returns the top-level package or module (e.g. ``pkg``). |
| 98 | |
| 99 | If you are dynamically importing a module that was created since the |
| 100 | interpreter began execution (e.g., created a Python source file), you may |
| 101 | need to call :func:`invalidate_caches` in order for the new module to be |
| 102 | noticed by the import system. |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 103 | |
Brett Cannon | 98620d8 | 2013-12-13 13:57:41 -0500 | [diff] [blame] | 104 | .. versionchanged:: 3.3 |
| 105 | Parent packages are automatically imported. |
| 106 | |
Brett Cannon | ee78a2b | 2012-05-12 17:43:17 -0400 | [diff] [blame] | 107 | .. function:: find_loader(name, path=None) |
| 108 | |
| 109 | Find the loader for a module, optionally within the specified *path*. If the |
| 110 | module is in :attr:`sys.modules`, then ``sys.modules[name].__loader__`` is |
Brett Cannon | 3279923 | 2013-03-13 11:09:08 -0700 | [diff] [blame] | 111 | returned (unless the loader would be ``None`` or is not set, in which case |
Brett Cannon | ee78a2b | 2012-05-12 17:43:17 -0400 | [diff] [blame] | 112 | :exc:`ValueError` is raised). Otherwise a search using :attr:`sys.meta_path` |
| 113 | is done. ``None`` is returned if no loader is found. |
| 114 | |
Brett Cannon | 56b4ca7 | 2012-11-17 09:30:55 -0500 | [diff] [blame] | 115 | A dotted name does not have its parent's implicitly imported as that requires |
| 116 | loading them and that may not be desired. To properly import a submodule you |
| 117 | will need to import all parent packages of the submodule and use the correct |
| 118 | argument to *path*. |
Brett Cannon | ee78a2b | 2012-05-12 17:43:17 -0400 | [diff] [blame] | 119 | |
Brett Cannon | 3279923 | 2013-03-13 11:09:08 -0700 | [diff] [blame] | 120 | .. versionadded:: 3.3 |
| 121 | |
| 122 | .. versionchanged:: 3.4 |
| 123 | If ``__loader__`` is not set, raise :exc:`ValueError`, just like when the |
| 124 | attribute is set to ``None``. |
| 125 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 126 | .. deprecated:: 3.4 |
Eric Snow | 6029e08 | 2014-01-25 15:32:46 -0700 | [diff] [blame] | 127 | Use :func:`importlib.util.find_spec` instead. |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 128 | |
Antoine Pitrou | c541f8e | 2012-02-20 01:48:16 +0100 | [diff] [blame] | 129 | .. function:: invalidate_caches() |
| 130 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 131 | Invalidate the internal caches of finders stored at |
| 132 | :data:`sys.meta_path`. If a finder implements ``invalidate_caches()`` then it |
Brett Cannon | 4067aa2 | 2013-04-27 23:20:32 -0400 | [diff] [blame] | 133 | will be called to perform the invalidation. This function should be called |
| 134 | if any modules are created/installed while your program is running to |
| 135 | guarantee all finders will notice the new module's existence. |
Antoine Pitrou | c541f8e | 2012-02-20 01:48:16 +0100 | [diff] [blame] | 136 | |
| 137 | .. versionadded:: 3.3 |
| 138 | |
Brett Cannon | 3fe35e6 | 2013-06-14 15:04:26 -0400 | [diff] [blame] | 139 | .. function:: reload(module) |
| 140 | |
| 141 | Reload a previously imported *module*. The argument must be a module object, |
| 142 | so it must have been successfully imported before. This is useful if you |
| 143 | have edited the module source file using an external editor and want to try |
| 144 | out the new version without leaving the Python interpreter. The return value |
Brett Cannon | 8ad3786 | 2013-10-25 13:52:46 -0400 | [diff] [blame] | 145 | is the module object (which can be different if re-importing causes a |
| 146 | different object to be placed in :data:`sys.modules`). |
Brett Cannon | 3fe35e6 | 2013-06-14 15:04:26 -0400 | [diff] [blame] | 147 | |
Brett Cannon | 8ad3786 | 2013-10-25 13:52:46 -0400 | [diff] [blame] | 148 | When :func:`reload` is executed: |
Brett Cannon | 3fe35e6 | 2013-06-14 15:04:26 -0400 | [diff] [blame] | 149 | |
Larry Hastings | 3732ed2 | 2014-03-15 21:13:56 -0700 | [diff] [blame] | 150 | * Python module's code is recompiled and the module-level code re-executed, |
Brett Cannon | 3fe35e6 | 2013-06-14 15:04:26 -0400 | [diff] [blame] | 151 | defining a new set of objects which are bound to names in the module's |
| 152 | dictionary by reusing the :term:`loader` which originally loaded the |
| 153 | module. The ``init`` function of extension modules is not called a second |
| 154 | time. |
| 155 | |
| 156 | * As with all other objects in Python the old objects are only reclaimed |
| 157 | after their reference counts drop to zero. |
| 158 | |
| 159 | * The names in the module namespace are updated to point to any new or |
| 160 | changed objects. |
| 161 | |
| 162 | * Other references to the old objects (such as names external to the module) are |
| 163 | not rebound to refer to the new objects and must be updated in each namespace |
| 164 | where they occur if that is desired. |
| 165 | |
| 166 | There are a number of other caveats: |
| 167 | |
Brett Cannon | 3fe35e6 | 2013-06-14 15:04:26 -0400 | [diff] [blame] | 168 | When a module is reloaded, its dictionary (containing the module's global |
| 169 | variables) is retained. Redefinitions of names will override the old |
| 170 | definitions, so this is generally not a problem. If the new version of a |
| 171 | module does not define a name that was defined by the old version, the old |
| 172 | definition remains. This feature can be used to the module's advantage if it |
| 173 | maintains a global table or cache of objects --- with a :keyword:`try` |
| 174 | statement it can test for the table's presence and skip its initialization if |
| 175 | desired:: |
| 176 | |
| 177 | try: |
| 178 | cache |
| 179 | except NameError: |
| 180 | cache = {} |
| 181 | |
| 182 | It is legal though generally not very useful to reload built-in or |
| 183 | dynamically loaded modules (this is not true for e.g. :mod:`sys`, |
Serhiy Storchaka | 98b28fd | 2013-10-13 23:12:09 +0300 | [diff] [blame] | 184 | :mod:`__main__`, :mod:`builtins` and other key modules where reloading is |
Brett Cannon | 3fe35e6 | 2013-06-14 15:04:26 -0400 | [diff] [blame] | 185 | frowned upon). In many cases, however, extension modules are not designed to |
| 186 | be initialized more than once, and may fail in arbitrary ways when reloaded. |
| 187 | |
| 188 | If a module imports objects from another module using :keyword:`from` ... |
| 189 | :keyword:`import` ..., calling :func:`reload` for the other module does not |
| 190 | redefine the objects imported from it --- one way around this is to |
| 191 | re-execute the :keyword:`from` statement, another is to use :keyword:`import` |
| 192 | and qualified names (*module.name*) instead. |
| 193 | |
| 194 | If a module instantiates instances of a class, reloading the module that |
| 195 | defines the class does not affect the method definitions of the instances --- |
| 196 | they continue to use the old class definition. The same is true for derived |
| 197 | classes. |
| 198 | |
| 199 | .. versionadded:: 3.4 |
| 200 | |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 201 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 202 | :mod:`importlib.abc` -- Abstract base classes related to import |
| 203 | --------------------------------------------------------------- |
| 204 | |
| 205 | .. module:: importlib.abc |
| 206 | :synopsis: Abstract base classes related to import |
| 207 | |
| 208 | The :mod:`importlib.abc` module contains all of the core abstract base classes |
| 209 | used by :keyword:`import`. Some subclasses of the core abstract base classes |
| 210 | are also provided to help in implementing the core ABCs. |
| 211 | |
Andrew Svetlov | a865654 | 2012-08-13 22:19:01 +0300 | [diff] [blame] | 212 | ABC hierarchy:: |
| 213 | |
| 214 | object |
Brett Cannon | 1b79918 | 2012-08-17 14:08:24 -0400 | [diff] [blame] | 215 | +-- Finder (deprecated) |
Andrew Svetlov | a865654 | 2012-08-13 22:19:01 +0300 | [diff] [blame] | 216 | | +-- MetaPathFinder |
| 217 | | +-- PathEntryFinder |
| 218 | +-- Loader |
| 219 | +-- ResourceLoader --------+ |
| 220 | +-- InspectLoader | |
| 221 | +-- ExecutionLoader --+ |
| 222 | +-- FileLoader |
| 223 | +-- SourceLoader |
Andrew Svetlov | a865654 | 2012-08-13 22:19:01 +0300 | [diff] [blame] | 224 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 225 | |
| 226 | .. class:: Finder |
| 227 | |
Brett Cannon | 1b79918 | 2012-08-17 14:08:24 -0400 | [diff] [blame] | 228 | An abstract base class representing a :term:`finder`. |
| 229 | |
| 230 | .. deprecated:: 3.3 |
| 231 | Use :class:`MetaPathFinder` or :class:`PathEntryFinder` instead. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 232 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 233 | .. method:: find_module(fullname, path=None) |
Brett Cannon | b46a179 | 2012-02-27 18:15:42 -0500 | [diff] [blame] | 234 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 235 | An abstact method for finding a :term:`loader` for the specified |
| 236 | module. Originally specified in :pep:`302`, this method was meant |
| 237 | for use in :data:`sys.meta_path` and in the path-based import subsystem. |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 238 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 239 | .. versionchanged:: 3.4 |
| 240 | Returns ``None`` when called instead of raising |
| 241 | :exc:`NotImplementedError`. |
| 242 | |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 243 | |
Brett Cannon | 077ef45 | 2012-08-02 17:50:06 -0400 | [diff] [blame] | 244 | .. class:: MetaPathFinder |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 245 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 246 | An abstract base class representing a :term:`meta path finder`. For |
| 247 | compatibility, this is a subclass of :class:`Finder`. |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 248 | |
| 249 | .. versionadded:: 3.3 |
| 250 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 251 | .. method:: find_spec(fullname, path, target=None) |
| 252 | |
| 253 | An abstract method for finding a :term:`spec <module spec>` for |
| 254 | the specified module. If this is a top-level import, *path* will |
| 255 | be ``None``. Otherwise, this is a search for a subpackage or |
| 256 | module and *path* will be the value of :attr:`__path__` from the |
| 257 | parent package. If a spec cannot be found, ``None`` is returned. |
| 258 | When passed in, ``target`` is a module object that the finder may |
| 259 | use to make a more educated about what spec to return. |
| 260 | |
| 261 | .. versionadded:: 3.4 |
| 262 | |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 263 | .. method:: find_module(fullname, path) |
| 264 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 265 | A legacy method for finding a :term:`loader` for the specified |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 266 | module. If this is a top-level import, *path* will be ``None``. |
Ezio Melotti | 1f67e80 | 2012-10-21 07:24:13 +0300 | [diff] [blame] | 267 | Otherwise, this is a search for a subpackage or module and *path* |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 268 | will be the value of :attr:`__path__` from the parent |
| 269 | package. If a loader cannot be found, ``None`` is returned. |
| 270 | |
Brett Cannon | 8d94229 | 2014-01-07 15:52:42 -0500 | [diff] [blame] | 271 | If :meth:`find_spec` is defined, backwards-compatible functionality is |
| 272 | provided. |
| 273 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 274 | .. versionchanged:: 3.4 |
| 275 | Returns ``None`` when called instead of raising |
Brett Cannon | 8d94229 | 2014-01-07 15:52:42 -0500 | [diff] [blame] | 276 | :exc:`NotImplementedError`. Can use :meth:`find_spec` to provide |
| 277 | functionality. |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 278 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 279 | .. deprecated:: 3.4 |
| 280 | Use :meth:`find_spec` instead. |
| 281 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 282 | .. method:: invalidate_caches() |
| 283 | |
| 284 | An optional method which, when called, should invalidate any internal |
Brett Cannon | a6e8581 | 2012-08-11 19:41:27 -0400 | [diff] [blame] | 285 | cache used by the finder. Used by :func:`importlib.invalidate_caches` |
| 286 | when invalidating the caches of all finders on :data:`sys.meta_path`. |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 287 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 288 | .. versionchanged:: 3.4 |
| 289 | Returns ``None`` when called instead of ``NotImplemented``. |
| 290 | |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 291 | |
Brett Cannon | 077ef45 | 2012-08-02 17:50:06 -0400 | [diff] [blame] | 292 | .. class:: PathEntryFinder |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 293 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 294 | An abstract base class representing a :term:`path entry finder`. Though |
| 295 | it bears some similarities to :class:`MetaPathFinder`, ``PathEntryFinder`` |
| 296 | is meant for use only within the path-based import subsystem provided |
| 297 | by :class:`PathFinder`. This ABC is a subclass of :class:`Finder` for |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 298 | compatibility reasons only. |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 299 | |
| 300 | .. versionadded:: 3.3 |
| 301 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 302 | .. method:: find_spec(fullname, target=None) |
| 303 | |
| 304 | An abstract method for finding a :term:`spec <module spec>` for |
| 305 | the specified module. The finder will search for the module only |
| 306 | within the :term:`path entry` to which it is assigned. If a spec |
| 307 | cannot be found, ``None`` is returned. When passed in, ``target`` |
| 308 | is a module object that the finder may use to make a more educated |
| 309 | about what spec to return. |
| 310 | |
| 311 | .. versionadded:: 3.4 |
| 312 | |
Brett Cannon | 4067aa2 | 2013-04-27 23:20:32 -0400 | [diff] [blame] | 313 | .. method:: find_loader(fullname) |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 314 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 315 | A legacy method for finding a :term:`loader` for the specified |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 316 | module. Returns a 2-tuple of ``(loader, portion)`` where ``portion`` |
| 317 | is a sequence of file system locations contributing to part of a namespace |
| 318 | package. The loader may be ``None`` while specifying ``portion`` to |
| 319 | signify the contribution of the file system locations to a namespace |
| 320 | package. An empty list can be used for ``portion`` to signify the loader |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 321 | is not part of a namespace package. If ``loader`` is ``None`` and |
| 322 | ``portion`` is the empty list then no loader or location for a namespace |
| 323 | package were found (i.e. failure to find anything for the module). |
| 324 | |
Brett Cannon | 8d94229 | 2014-01-07 15:52:42 -0500 | [diff] [blame] | 325 | If :meth:`find_spec` is defined then backwards-compatible functionality is |
| 326 | provided. |
| 327 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 328 | .. versionchanged:: 3.4 |
| 329 | Returns ``(None, [])`` instead of raising :exc:`NotImplementedError`. |
Brett Cannon | 8d94229 | 2014-01-07 15:52:42 -0500 | [diff] [blame] | 330 | Uses :meth:`find_spec` when available to provide functionality. |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 331 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 332 | .. deprecated:: 3.4 |
| 333 | Use :meth:`find_spec` instead. |
| 334 | |
Brett Cannon | 4067aa2 | 2013-04-27 23:20:32 -0400 | [diff] [blame] | 335 | .. method:: find_module(fullname) |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 336 | |
| 337 | A concrete implementation of :meth:`Finder.find_module` which is |
| 338 | equivalent to ``self.find_loader(fullname)[0]``. |
| 339 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 340 | .. deprecated:: 3.4 |
| 341 | Use :meth:`find_spec` instead. |
| 342 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 343 | .. method:: invalidate_caches() |
| 344 | |
| 345 | An optional method which, when called, should invalidate any internal |
Brett Cannon | a6e8581 | 2012-08-11 19:41:27 -0400 | [diff] [blame] | 346 | cache used by the finder. Used by :meth:`PathFinder.invalidate_caches` |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 347 | when invalidating the caches of all cached finders. |
Brett Cannon | b46a179 | 2012-02-27 18:15:42 -0500 | [diff] [blame] | 348 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 349 | |
| 350 | .. class:: Loader |
| 351 | |
| 352 | An abstract base class for a :term:`loader`. |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 353 | See :pep:`302` for the exact definition for a loader. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 354 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 355 | .. method:: create_module(spec) |
| 356 | |
Brett Cannon | 02d8454 | 2015-01-09 11:39:21 -0500 | [diff] [blame] | 357 | A method that returns the module object to use when |
| 358 | importing a module. This method may return ``None``, |
| 359 | indicating that default module creation semantics should take place. |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 360 | |
| 361 | .. versionadded:: 3.4 |
| 362 | |
Brett Cannon | 02d8454 | 2015-01-09 11:39:21 -0500 | [diff] [blame] | 363 | .. versionchanged:: 3.5 |
| 364 | Starting in Python 3.6, this method will not be optional when |
| 365 | :meth:`exec_module` is defined. |
| 366 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 367 | .. method:: exec_module(module) |
| 368 | |
| 369 | An abstract method that executes the module in its own namespace |
| 370 | when a module is imported or reloaded. The module should already |
| 371 | be initialized when exec_module() is called. |
| 372 | |
| 373 | .. versionadded:: 3.4 |
| 374 | |
Brett Cannon | 9c751b7 | 2009-03-09 16:28:16 +0000 | [diff] [blame] | 375 | .. method:: load_module(fullname) |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 376 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 377 | A legacy method for loading a module. If the module cannot be |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 378 | loaded, :exc:`ImportError` is raised, otherwise the loaded module is |
| 379 | returned. |
| 380 | |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 381 | If the requested module already exists in :data:`sys.modules`, that |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 382 | module should be used and reloaded. |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 383 | Otherwise the loader should create a new module and insert it into |
| 384 | :data:`sys.modules` before any loading begins, to prevent recursion |
| 385 | from the import. If the loader inserted a module and the load fails, it |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 386 | must be removed by the loader from :data:`sys.modules`; modules already |
| 387 | in :data:`sys.modules` before the loader began execution should be left |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 388 | alone (see :func:`importlib.util.module_for_loader`). |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 389 | |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 390 | The loader should set several attributes on the module. |
| 391 | (Note that some of these attributes can change when a module is |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 392 | reloaded): |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 393 | |
| 394 | - :attr:`__name__` |
| 395 | The name of the module. |
| 396 | |
| 397 | - :attr:`__file__` |
| 398 | The path to where the module data is stored (not set for built-in |
| 399 | modules). |
| 400 | |
Brett Cannon | 2cefb3c | 2013-05-25 11:26:11 -0400 | [diff] [blame] | 401 | - :attr:`__cached__` |
| 402 | The path to where a compiled version of the module is/should be |
| 403 | stored (not set when the attribute would be inappropriate). |
| 404 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 405 | - :attr:`__path__` |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 406 | A list of strings specifying the search path within a |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 407 | package. This attribute is not set on modules. |
| 408 | |
| 409 | - :attr:`__package__` |
| 410 | The parent package for the module/package. If the module is |
| 411 | top-level then it has a value of the empty string. The |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 412 | :func:`importlib.util.module_for_loader` decorator can handle the |
| 413 | details for :attr:`__package__`. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 414 | |
| 415 | - :attr:`__loader__` |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 416 | The loader used to load the module. The |
| 417 | :func:`importlib.util.module_for_loader` decorator can handle the |
| 418 | details for :attr:`__package__`. |
| 419 | |
Brett Cannon | 8d94229 | 2014-01-07 15:52:42 -0500 | [diff] [blame] | 420 | When :meth:`exec_module` is available then backwards-compatible |
| 421 | functionality is provided. |
| 422 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 423 | .. versionchanged:: 3.4 |
| 424 | Raise :exc:`ImportError` when called instead of |
Brett Cannon | 8d94229 | 2014-01-07 15:52:42 -0500 | [diff] [blame] | 425 | :exc:`NotImplementedError`. Functionality provided when |
| 426 | :meth:`exec_module` is available. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 427 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 428 | .. deprecated:: 3.4 |
| 429 | The recommended API for loading a module is :meth:`exec_module` |
Brett Cannon | 02d8454 | 2015-01-09 11:39:21 -0500 | [diff] [blame] | 430 | (and :meth:`create_module`). Loaders should implement |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 431 | it instead of load_module(). The import machinery takes care of |
| 432 | all the other responsibilities of load_module() when exec_module() |
| 433 | is implemented. |
| 434 | |
Barry Warsaw | d7d2194 | 2012-07-29 16:36:17 -0400 | [diff] [blame] | 435 | .. method:: module_repr(module) |
| 436 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 437 | A legacy method which when implemented calculates and returns the |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 438 | given module's repr, as a string. The module type's default repr() will |
| 439 | use the result of this method as appropriate. |
Barry Warsaw | d7d2194 | 2012-07-29 16:36:17 -0400 | [diff] [blame] | 440 | |
Georg Brandl | 526575d | 2013-04-11 16:10:13 +0200 | [diff] [blame] | 441 | .. versionadded:: 3.3 |
Barry Warsaw | d7d2194 | 2012-07-29 16:36:17 -0400 | [diff] [blame] | 442 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 443 | .. versionchanged:: 3.4 |
Georg Brandl | 526575d | 2013-04-11 16:10:13 +0200 | [diff] [blame] | 444 | Made optional instead of an abstractmethod. |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 445 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 446 | .. deprecated:: 3.4 |
| 447 | The import machinery now takes care of this automatically. |
| 448 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 449 | |
| 450 | .. class:: ResourceLoader |
| 451 | |
| 452 | An abstract base class for a :term:`loader` which implements the optional |
| 453 | :pep:`302` protocol for loading arbitrary resources from the storage |
| 454 | back-end. |
| 455 | |
Brett Cannon | 9c751b7 | 2009-03-09 16:28:16 +0000 | [diff] [blame] | 456 | .. method:: get_data(path) |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 457 | |
| 458 | An abstract method to return the bytes for the data located at *path*. |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 459 | Loaders that have a file-like storage back-end |
Brett Cannon | 16248a4 | 2009-04-01 20:47:14 +0000 | [diff] [blame] | 460 | that allows storing arbitrary data |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 461 | can implement this abstract method to give direct access |
Andrew Svetlov | 08af000 | 2014-04-01 01:13:30 +0300 | [diff] [blame] | 462 | to the data stored. :exc:`OSError` is to be raised if the *path* cannot |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 463 | be found. The *path* is expected to be constructed using a module's |
Brett Cannon | 16248a4 | 2009-04-01 20:47:14 +0000 | [diff] [blame] | 464 | :attr:`__file__` attribute or an item from a package's :attr:`__path__`. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 465 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 466 | .. versionchanged:: 3.4 |
Andrew Svetlov | 08af000 | 2014-04-01 01:13:30 +0300 | [diff] [blame] | 467 | Raises :exc:`OSError` instead of :exc:`NotImplementedError`. |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 468 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 469 | |
| 470 | .. class:: InspectLoader |
| 471 | |
| 472 | An abstract base class for a :term:`loader` which implements the optional |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 473 | :pep:`302` protocol for loaders that inspect modules. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 474 | |
Brett Cannon | a113ac5 | 2009-03-15 01:41:33 +0000 | [diff] [blame] | 475 | .. method:: get_code(fullname) |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 476 | |
R David Murray | 0ae7ae1 | 2014-01-08 18:16:02 -0500 | [diff] [blame] | 477 | Return the code object for a module, or ``None`` if the module does not |
| 478 | have a code object (as would be the case, for example, for a built-in |
| 479 | module). Raise an :exc:`ImportError` if loader cannot find the |
| 480 | requested module. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 481 | |
Brett Cannon | 3b62ca8 | 2013-05-27 21:11:04 -0400 | [diff] [blame] | 482 | .. note:: |
| 483 | While the method has a default implementation, it is suggested that |
| 484 | it be overridden if possible for performance. |
| 485 | |
R David Murray | 1b00f25 | 2012-08-15 10:43:58 -0400 | [diff] [blame] | 486 | .. index:: |
| 487 | single: universal newlines; importlib.abc.InspectLoader.get_source method |
| 488 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 489 | .. versionchanged:: 3.4 |
Brett Cannon | 3b62ca8 | 2013-05-27 21:11:04 -0400 | [diff] [blame] | 490 | No longer abstract and a concrete implementation is provided. |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 491 | |
Brett Cannon | 9c751b7 | 2009-03-09 16:28:16 +0000 | [diff] [blame] | 492 | .. method:: get_source(fullname) |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 493 | |
| 494 | An abstract method to return the source of a module. It is returned as |
R David Murray | 1b00f25 | 2012-08-15 10:43:58 -0400 | [diff] [blame] | 495 | a text string using :term:`universal newlines`, translating all |
R David Murray | ee0a945 | 2012-08-15 11:05:36 -0400 | [diff] [blame] | 496 | recognized line separators into ``'\n'`` characters. Returns ``None`` |
| 497 | if no source is available (e.g. a built-in module). Raises |
| 498 | :exc:`ImportError` if the loader cannot find the module specified. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 499 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 500 | .. versionchanged:: 3.4 |
| 501 | Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. |
| 502 | |
Brett Cannon | a113ac5 | 2009-03-15 01:41:33 +0000 | [diff] [blame] | 503 | .. method:: is_package(fullname) |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 504 | |
Brett Cannon | a113ac5 | 2009-03-15 01:41:33 +0000 | [diff] [blame] | 505 | An abstract method to return a true value if the module is a package, a |
| 506 | false value otherwise. :exc:`ImportError` is raised if the |
| 507 | :term:`loader` cannot find the module. |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 508 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 509 | .. versionchanged:: 3.4 |
| 510 | Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. |
| 511 | |
Brett Cannon | 6eaac13 | 2014-05-09 12:28:22 -0400 | [diff] [blame] | 512 | .. staticmethod:: source_to_code(data, path='<string>') |
Brett Cannon | 9ffe85e | 2013-05-26 16:45:10 -0400 | [diff] [blame] | 513 | |
| 514 | Create a code object from Python source. |
| 515 | |
| 516 | The *data* argument can be whatever the :func:`compile` function |
| 517 | supports (i.e. string or bytes). The *path* argument should be |
| 518 | the "path" to where the source code originated from, which can be an |
| 519 | abstract concept (e.g. location in a zip file). |
| 520 | |
Brett Cannon | 6eaac13 | 2014-05-09 12:28:22 -0400 | [diff] [blame] | 521 | With the subsequent code object one can execute it in a module by |
| 522 | running ``exec(code, module.__dict__)``. |
| 523 | |
Brett Cannon | 9ffe85e | 2013-05-26 16:45:10 -0400 | [diff] [blame] | 524 | .. versionadded:: 3.4 |
| 525 | |
Brett Cannon | 6eaac13 | 2014-05-09 12:28:22 -0400 | [diff] [blame] | 526 | .. versionchanged:: 3.5 |
| 527 | Made the method static. |
| 528 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 529 | .. method:: exec_module(module) |
| 530 | |
| 531 | Implementation of :meth:`Loader.exec_module`. |
| 532 | |
| 533 | .. versionadded:: 3.4 |
| 534 | |
Brett Cannon | 0dbb4c7 | 2013-05-31 18:56:47 -0400 | [diff] [blame] | 535 | .. method:: load_module(fullname) |
| 536 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 537 | Implementation of :meth:`Loader.load_module`. |
| 538 | |
| 539 | .. deprecated:: 3.4 |
| 540 | use :meth:`exec_module` instead. |
Brett Cannon | 0dbb4c7 | 2013-05-31 18:56:47 -0400 | [diff] [blame] | 541 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 542 | |
Brett Cannon | 6919427 | 2009-07-20 04:23:48 +0000 | [diff] [blame] | 543 | .. class:: ExecutionLoader |
| 544 | |
| 545 | An abstract base class which inherits from :class:`InspectLoader` that, |
Brett Cannon | 2346029 | 2009-07-20 22:59:00 +0000 | [diff] [blame] | 546 | when implemented, helps a module to be executed as a script. The ABC |
Brett Cannon | 6919427 | 2009-07-20 04:23:48 +0000 | [diff] [blame] | 547 | represents an optional :pep:`302` protocol. |
| 548 | |
| 549 | .. method:: get_filename(fullname) |
| 550 | |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 551 | An abstract method that is to return the value of :attr:`__file__` for |
Brett Cannon | 6919427 | 2009-07-20 04:23:48 +0000 | [diff] [blame] | 552 | the specified module. If no path is available, :exc:`ImportError` is |
| 553 | raised. |
| 554 | |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 555 | If source code is available, then the method should return the path to |
| 556 | the source file, regardless of whether a bytecode was used to load the |
| 557 | module. |
| 558 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 559 | .. versionchanged:: 3.4 |
| 560 | Raises :exc:`ImportError` instead of :exc:`NotImplementedError`. |
| 561 | |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 562 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 563 | .. class:: FileLoader(fullname, path) |
| 564 | |
| 565 | An abstract base class which inherits from :class:`ResourceLoader` and |
Andrew Svetlov | a60de4f | 2013-02-17 16:55:58 +0200 | [diff] [blame] | 566 | :class:`ExecutionLoader`, providing concrete implementations of |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 567 | :meth:`ResourceLoader.get_data` and :meth:`ExecutionLoader.get_filename`. |
| 568 | |
| 569 | The *fullname* argument is a fully resolved name of the module the loader is |
| 570 | to handle. The *path* argument is the path to the file for the module. |
| 571 | |
| 572 | .. versionadded:: 3.3 |
| 573 | |
| 574 | .. attribute:: name |
| 575 | |
| 576 | The name of the module the loader can handle. |
| 577 | |
| 578 | .. attribute:: path |
| 579 | |
| 580 | Path to the file of the module. |
| 581 | |
Barry Warsaw | d7d2194 | 2012-07-29 16:36:17 -0400 | [diff] [blame] | 582 | .. method:: load_module(fullname) |
Brett Cannon | c049952 | 2012-05-11 14:48:41 -0400 | [diff] [blame] | 583 | |
Barry Warsaw | d7d2194 | 2012-07-29 16:36:17 -0400 | [diff] [blame] | 584 | Calls super's ``load_module()``. |
Brett Cannon | c049952 | 2012-05-11 14:48:41 -0400 | [diff] [blame] | 585 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 586 | .. deprecated:: 3.4 |
| 587 | Use :meth:`Loader.exec_module` instead. |
| 588 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 589 | .. method:: get_filename(fullname) |
| 590 | |
Barry Warsaw | d7d2194 | 2012-07-29 16:36:17 -0400 | [diff] [blame] | 591 | Returns :attr:`path`. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 592 | |
| 593 | .. method:: get_data(path) |
| 594 | |
Brett Cannon | 3b62ca8 | 2013-05-27 21:11:04 -0400 | [diff] [blame] | 595 | Reads *path* as a binary file and returns the bytes from it. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 596 | |
| 597 | |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 598 | .. class:: SourceLoader |
| 599 | |
| 600 | An abstract base class for implementing source (and optionally bytecode) |
| 601 | file loading. The class inherits from both :class:`ResourceLoader` and |
| 602 | :class:`ExecutionLoader`, requiring the implementation of: |
| 603 | |
| 604 | * :meth:`ResourceLoader.get_data` |
| 605 | * :meth:`ExecutionLoader.get_filename` |
Brett Cannon | 6dfbff3 | 2010-07-21 09:48:31 +0000 | [diff] [blame] | 606 | Should only return the path to the source file; sourceless |
Brett Cannon | a81d527 | 2013-06-16 19:17:12 -0400 | [diff] [blame] | 607 | loading is not supported. |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 608 | |
| 609 | The abstract methods defined by this class are to add optional bytecode |
Brett Cannon | 5650e4f | 2012-11-18 10:03:31 -0500 | [diff] [blame] | 610 | file support. Not implementing these optional methods (or causing them to |
| 611 | raise :exc:`NotImplementedError`) causes the loader to |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 612 | only work with source code. Implementing the methods allows the loader to |
| 613 | work with source *and* bytecode files; it does not allow for *sourceless* |
| 614 | loading where only bytecode is provided. Bytecode files are an |
| 615 | optimization to speed up loading by removing the parsing step of Python's |
| 616 | compiler, and so no bytecode-specific API is exposed. |
| 617 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 618 | .. method:: path_stats(path) |
Antoine Pitrou | 5136ac0 | 2012-01-13 18:52:16 +0100 | [diff] [blame] | 619 | |
| 620 | Optional abstract method which returns a :class:`dict` containing |
| 621 | metadata about the specifed path. Supported dictionary keys are: |
| 622 | |
| 623 | - ``'mtime'`` (mandatory): an integer or floating-point number |
| 624 | representing the modification time of the source code; |
| 625 | - ``'size'`` (optional): the size in bytes of the source code. |
| 626 | |
| 627 | Any other keys in the dictionary are ignored, to allow for future |
Andrew Svetlov | 08af000 | 2014-04-01 01:13:30 +0300 | [diff] [blame] | 628 | extensions. If the path cannot be handled, :exc:`OSError` is raised. |
Antoine Pitrou | 5136ac0 | 2012-01-13 18:52:16 +0100 | [diff] [blame] | 629 | |
| 630 | .. versionadded:: 3.3 |
| 631 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 632 | .. versionchanged:: 3.4 |
Andrew Svetlov | 08af000 | 2014-04-01 01:13:30 +0300 | [diff] [blame] | 633 | Raise :exc:`OSError` instead of :exc:`NotImplementedError`. |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 634 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 635 | .. method:: path_mtime(path) |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 636 | |
| 637 | Optional abstract method which returns the modification time for the |
| 638 | specified path. |
| 639 | |
Antoine Pitrou | 5136ac0 | 2012-01-13 18:52:16 +0100 | [diff] [blame] | 640 | .. deprecated:: 3.3 |
| 641 | This method is deprecated in favour of :meth:`path_stats`. You don't |
| 642 | have to implement it, but it is still available for compatibility |
Andrew Svetlov | 08af000 | 2014-04-01 01:13:30 +0300 | [diff] [blame] | 643 | purposes. Raise :exc:`OSError` if the path cannot be handled. |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 644 | |
Georg Brandl | df48b97 | 2014-03-24 09:06:18 +0100 | [diff] [blame] | 645 | .. versionchanged:: 3.4 |
Andrew Svetlov | 08af000 | 2014-04-01 01:13:30 +0300 | [diff] [blame] | 646 | Raise :exc:`OSError` instead of :exc:`NotImplementedError`. |
Antoine Pitrou | 5136ac0 | 2012-01-13 18:52:16 +0100 | [diff] [blame] | 647 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 648 | .. method:: set_data(path, data) |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 649 | |
| 650 | Optional abstract method which writes the specified bytes to a file |
Brett Cannon | 61b1425 | 2010-07-03 21:48:25 +0000 | [diff] [blame] | 651 | path. Any intermediate directories which do not exist are to be created |
| 652 | automatically. |
| 653 | |
| 654 | When writing to the path fails because the path is read-only |
Brett Cannon | 2cefb3c | 2013-05-25 11:26:11 -0400 | [diff] [blame] | 655 | (:attr:`errno.EACCES`/:exc:`PermissionError`), do not propagate the |
| 656 | exception. |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 657 | |
Brett Cannon | 100883f | 2013-04-09 16:59:39 -0400 | [diff] [blame] | 658 | .. versionchanged:: 3.4 |
| 659 | No longer raises :exc:`NotImplementedError` when called. |
| 660 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 661 | .. method:: get_code(fullname) |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 662 | |
| 663 | Concrete implementation of :meth:`InspectLoader.get_code`. |
| 664 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 665 | .. method:: exec_module(module) |
| 666 | |
| 667 | Concrete implementation of :meth:`Loader.exec_module`. |
| 668 | |
| 669 | .. versionadded:: 3.4 |
| 670 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 671 | .. method:: load_module(fullname) |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 672 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 673 | Concrete implementation of :meth:`Loader.load_module`. |
| 674 | |
| 675 | .. deprecated:: 3.4 |
| 676 | Use :meth:`exec_module` instead. |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 677 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 678 | .. method:: get_source(fullname) |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 679 | |
| 680 | Concrete implementation of :meth:`InspectLoader.get_source`. |
| 681 | |
Brett Cannon | 773468f | 2012-08-02 17:35:34 -0400 | [diff] [blame] | 682 | .. method:: is_package(fullname) |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 683 | |
| 684 | Concrete implementation of :meth:`InspectLoader.is_package`. A module |
Brett Cannon | ea0b823 | 2012-06-15 20:00:53 -0400 | [diff] [blame] | 685 | is determined to be a package if its file path (as provided by |
| 686 | :meth:`ExecutionLoader.get_filename`) is a file named |
| 687 | ``__init__`` when the file extension is removed **and** the module name |
| 688 | itself does not end in ``__init__``. |
Brett Cannon | f23e374 | 2010-06-27 23:57:46 +0000 | [diff] [blame] | 689 | |
Brett Cannon | 6919427 | 2009-07-20 04:23:48 +0000 | [diff] [blame] | 690 | |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 691 | :mod:`importlib.machinery` -- Importers and path hooks |
| 692 | ------------------------------------------------------ |
| 693 | |
| 694 | .. module:: importlib.machinery |
| 695 | :synopsis: Importers and path hooks |
| 696 | |
| 697 | This module contains the various objects that help :keyword:`import` |
| 698 | find and load modules. |
| 699 | |
Brett Cannon | cb66eb0 | 2012-05-11 12:58:42 -0400 | [diff] [blame] | 700 | .. attribute:: SOURCE_SUFFIXES |
| 701 | |
| 702 | A list of strings representing the recognized file suffixes for source |
| 703 | modules. |
| 704 | |
| 705 | .. versionadded:: 3.3 |
| 706 | |
| 707 | .. attribute:: DEBUG_BYTECODE_SUFFIXES |
| 708 | |
| 709 | A list of strings representing the file suffixes for non-optimized bytecode |
| 710 | modules. |
| 711 | |
| 712 | .. versionadded:: 3.3 |
| 713 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 714 | .. deprecated:: 3.5 |
| 715 | Use :attr:`BYTECODE_SUFFIXES` instead. |
| 716 | |
Brett Cannon | cb66eb0 | 2012-05-11 12:58:42 -0400 | [diff] [blame] | 717 | .. attribute:: OPTIMIZED_BYTECODE_SUFFIXES |
| 718 | |
| 719 | A list of strings representing the file suffixes for optimized bytecode |
| 720 | modules. |
| 721 | |
| 722 | .. versionadded:: 3.3 |
| 723 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 724 | .. deprecated:: 3.5 |
| 725 | Use :attr:`BYTECODE_SUFFIXES` instead. |
| 726 | |
Brett Cannon | cb66eb0 | 2012-05-11 12:58:42 -0400 | [diff] [blame] | 727 | .. attribute:: BYTECODE_SUFFIXES |
| 728 | |
| 729 | A list of strings representing the recognized file suffixes for bytecode |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 730 | modules (including the leading dot). |
Brett Cannon | cb66eb0 | 2012-05-11 12:58:42 -0400 | [diff] [blame] | 731 | |
| 732 | .. versionadded:: 3.3 |
| 733 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 734 | .. versionchanged:: 3.5 |
| 735 | The value is no longer dependent on ``__debug__``. |
| 736 | |
Brett Cannon | cb66eb0 | 2012-05-11 12:58:42 -0400 | [diff] [blame] | 737 | .. attribute:: EXTENSION_SUFFIXES |
| 738 | |
Nick Coghlan | 76e0770 | 2012-07-18 23:14:57 +1000 | [diff] [blame] | 739 | A list of strings representing the recognized file suffixes for |
Brett Cannon | cb66eb0 | 2012-05-11 12:58:42 -0400 | [diff] [blame] | 740 | extension modules. |
| 741 | |
| 742 | .. versionadded:: 3.3 |
| 743 | |
Nick Coghlan | c5afd42 | 2012-07-18 23:59:08 +1000 | [diff] [blame] | 744 | .. function:: all_suffixes() |
Nick Coghlan | 76e0770 | 2012-07-18 23:14:57 +1000 | [diff] [blame] | 745 | |
| 746 | Returns a combined list of strings representing all file suffixes for |
Nick Coghlan | c5afd42 | 2012-07-18 23:59:08 +1000 | [diff] [blame] | 747 | modules recognized by the standard import machinery. This is a |
Nick Coghlan | 76e0770 | 2012-07-18 23:14:57 +1000 | [diff] [blame] | 748 | helper for code which simply needs to know if a filesystem path |
Nick Coghlan | c5afd42 | 2012-07-18 23:59:08 +1000 | [diff] [blame] | 749 | potentially refers to a module without needing any details on the kind |
| 750 | of module (for example, :func:`inspect.getmodulename`) |
Nick Coghlan | 76e0770 | 2012-07-18 23:14:57 +1000 | [diff] [blame] | 751 | |
| 752 | .. versionadded:: 3.3 |
| 753 | |
| 754 | |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 755 | .. class:: BuiltinImporter |
| 756 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 757 | An :term:`importer` for built-in modules. All known built-in modules are |
| 758 | listed in :data:`sys.builtin_module_names`. This class implements the |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 759 | :class:`importlib.abc.MetaPathFinder` and |
| 760 | :class:`importlib.abc.InspectLoader` ABCs. |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 761 | |
| 762 | Only class methods are defined by this class to alleviate the need for |
| 763 | instantiation. |
| 764 | |
Nick Coghlan | d5cacbb | 2015-05-23 22:24:10 +1000 | [diff] [blame] | 765 | .. versionchanged:: 3.5 |
| 766 | As part of :pep:`489`, the builtin importer now implements |
| 767 | :meth:`Loader.create_module` and :meth:`Loader.exec_module` |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 768 | |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 769 | |
| 770 | .. class:: FrozenImporter |
| 771 | |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 772 | An :term:`importer` for frozen modules. This class implements the |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 773 | :class:`importlib.abc.MetaPathFinder` and |
| 774 | :class:`importlib.abc.InspectLoader` ABCs. |
Brett Cannon | 78246b6 | 2009-01-25 04:56:30 +0000 | [diff] [blame] | 775 | |
| 776 | Only class methods are defined by this class to alleviate the need for |
| 777 | instantiation. |
| 778 | |
Brett Cannon | debb98d | 2009-02-16 04:18:01 +0000 | [diff] [blame] | 779 | |
Nick Coghlan | ff79486 | 2012-08-02 21:45:24 +1000 | [diff] [blame] | 780 | .. class:: WindowsRegistryFinder |
| 781 | |
| 782 | :term:`Finder` for modules declared in the Windows registry. This class |
Nick Coghlan | 4941774 | 2012-08-02 23:03:58 +1000 | [diff] [blame] | 783 | implements the :class:`importlib.abc.Finder` ABC. |
Nick Coghlan | ff79486 | 2012-08-02 21:45:24 +1000 | [diff] [blame] | 784 | |
| 785 | Only class methods are defined by this class to alleviate the need for |
| 786 | instantiation. |
| 787 | |
| 788 | .. versionadded:: 3.3 |
| 789 | |
| 790 | |
Brett Cannon | debb98d | 2009-02-16 04:18:01 +0000 | [diff] [blame] | 791 | .. class:: PathFinder |
| 792 | |
Brett Cannon | 1b79918 | 2012-08-17 14:08:24 -0400 | [diff] [blame] | 793 | A :term:`Finder` for :data:`sys.path` and package ``__path__`` attributes. |
| 794 | This class implements the :class:`importlib.abc.MetaPathFinder` ABC. |
Brett Cannon | debb98d | 2009-02-16 04:18:01 +0000 | [diff] [blame] | 795 | |
Brett Cannon | 1b79918 | 2012-08-17 14:08:24 -0400 | [diff] [blame] | 796 | Only class methods are defined by this class to alleviate the need for |
| 797 | instantiation. |
Brett Cannon | debb98d | 2009-02-16 04:18:01 +0000 | [diff] [blame] | 798 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 799 | .. classmethod:: find_spec(fullname, path=None, target=None) |
| 800 | |
| 801 | Class method that attempts to find a :term:`spec <module spec>` |
| 802 | for the module specified by *fullname* on :data:`sys.path` or, if |
| 803 | defined, on *path*. For each path entry that is searched, |
| 804 | :data:`sys.path_importer_cache` is checked. If a non-false object |
| 805 | is found then it is used as the :term:`path entry finder` to look |
| 806 | for the module being searched for. If no entry is found in |
| 807 | :data:`sys.path_importer_cache`, then :data:`sys.path_hooks` is |
| 808 | searched for a finder for the path entry and, if found, is stored |
| 809 | in :data:`sys.path_importer_cache` along with being queried about |
| 810 | the module. If no finder is ever found then ``None`` is both |
| 811 | stored in the cache and returned. |
| 812 | |
| 813 | .. versionadded:: 3.4 |
| 814 | |
Brett Cannon | b6e2556 | 2014-11-21 12:19:28 -0500 | [diff] [blame] | 815 | .. versionchanged:: 3.5 |
| 816 | If the current working directory -- represented by an empty string -- |
| 817 | is no longer valid then ``None`` is returned but no value is cached |
| 818 | in :data:`sys.path_importer_cache`. |
| 819 | |
Brett Cannon | 1b79918 | 2012-08-17 14:08:24 -0400 | [diff] [blame] | 820 | .. classmethod:: find_module(fullname, path=None) |
Brett Cannon | debb98d | 2009-02-16 04:18:01 +0000 | [diff] [blame] | 821 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 822 | A legacy wrapper around :meth:`find_spec`. |
| 823 | |
| 824 | .. deprecated:: 3.4 |
| 825 | Use :meth:`find_spec` instead. |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 826 | |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 827 | .. classmethod:: invalidate_caches() |
| 828 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 829 | Calls :meth:`importlib.abc.PathEntryFinder.invalidate_caches` on all |
| 830 | finders stored in :attr:`sys.path_importer_cache`. |
Brett Cannon | f4dc920 | 2012-08-10 12:21:12 -0400 | [diff] [blame] | 831 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 832 | .. versionchanged:: 3.4 |
| 833 | Calls objects in :data:`sys.path_hooks` with the current working |
| 834 | directory for ``''`` (i.e. the empty string). |
Brett Cannon | 27e27f7 | 2013-10-18 11:39:04 -0400 | [diff] [blame] | 835 | |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 836 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 837 | .. class:: FileFinder(path, \*loader_details) |
| 838 | |
Nick Coghlan | 8a9080f | 2012-08-02 21:26:03 +1000 | [diff] [blame] | 839 | A concrete implementation of :class:`importlib.abc.PathEntryFinder` which |
| 840 | caches results from the file system. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 841 | |
| 842 | The *path* argument is the directory for which the finder is in charge of |
| 843 | searching. |
| 844 | |
Brett Cannon | ac9f2f3 | 2012-08-10 13:47:54 -0400 | [diff] [blame] | 845 | The *loader_details* argument is a variable number of 2-item tuples each |
| 846 | containing a loader and a sequence of file suffixes the loader recognizes. |
Brett Cannon | 29b2f17 | 2013-06-21 18:31:55 -0400 | [diff] [blame] | 847 | The loaders are expected to be callables which accept two arguments of |
| 848 | the module's name and the path to the file found. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 849 | |
| 850 | The finder will cache the directory contents as necessary, making stat calls |
| 851 | for each module search to verify the cache is not outdated. Because cache |
| 852 | staleness relies upon the granularity of the operating system's state |
| 853 | information of the file system, there is a potential race condition of |
| 854 | searching for a module, creating a new file, and then searching for the |
| 855 | module the new file represents. If the operations happen fast enough to fit |
| 856 | within the granularity of stat calls, then the module search will fail. To |
| 857 | prevent this from happening, when you create a module dynamically, make sure |
| 858 | to call :func:`importlib.invalidate_caches`. |
| 859 | |
| 860 | .. versionadded:: 3.3 |
| 861 | |
| 862 | .. attribute:: path |
| 863 | |
| 864 | The path the finder will search in. |
| 865 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 866 | .. method:: find_spec(fullname, target=None) |
| 867 | |
| 868 | Attempt to find the spec to handle *fullname* within :attr:`path`. |
| 869 | |
| 870 | .. versionadded:: 3.4 |
| 871 | |
Brett Cannon | 1d75382 | 2013-06-16 19:06:55 -0400 | [diff] [blame] | 872 | .. method:: find_loader(fullname) |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 873 | |
| 874 | Attempt to find the loader to handle *fullname* within :attr:`path`. |
| 875 | |
| 876 | .. method:: invalidate_caches() |
| 877 | |
| 878 | Clear out the internal cache. |
| 879 | |
| 880 | .. classmethod:: path_hook(\*loader_details) |
| 881 | |
| 882 | A class method which returns a closure for use on :attr:`sys.path_hooks`. |
| 883 | An instance of :class:`FileFinder` is returned by the closure using the |
| 884 | path argument given to the closure directly and *loader_details* |
| 885 | indirectly. |
| 886 | |
| 887 | If the argument to the closure is not an existing directory, |
| 888 | :exc:`ImportError` is raised. |
| 889 | |
| 890 | |
| 891 | .. class:: SourceFileLoader(fullname, path) |
| 892 | |
| 893 | A concrete implementation of :class:`importlib.abc.SourceLoader` by |
| 894 | subclassing :class:`importlib.abc.FileLoader` and providing some concrete |
| 895 | implementations of other methods. |
| 896 | |
| 897 | .. versionadded:: 3.3 |
| 898 | |
| 899 | .. attribute:: name |
| 900 | |
| 901 | The name of the module that this loader will handle. |
| 902 | |
| 903 | .. attribute:: path |
| 904 | |
| 905 | The path to the source file. |
| 906 | |
| 907 | .. method:: is_package(fullname) |
| 908 | |
| 909 | Return true if :attr:`path` appears to be for a package. |
| 910 | |
| 911 | .. method:: path_stats(path) |
| 912 | |
| 913 | Concrete implementation of :meth:`importlib.abc.SourceLoader.path_stats`. |
| 914 | |
| 915 | .. method:: set_data(path, data) |
| 916 | |
| 917 | Concrete implementation of :meth:`importlib.abc.SourceLoader.set_data`. |
| 918 | |
Brett Cannon | 062fcac | 2014-05-09 11:55:49 -0400 | [diff] [blame] | 919 | .. method:: load_module(name=None) |
| 920 | |
| 921 | Concrete implementation of :meth:`importlib.abc.Loader.load_module` where |
| 922 | specifying the name of the module to load is optional. |
| 923 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 924 | |
Marc-Andre Lemburg | 4fe29c9 | 2012-04-25 02:31:37 +0200 | [diff] [blame] | 925 | .. class:: SourcelessFileLoader(fullname, path) |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 926 | |
| 927 | A concrete implementation of :class:`importlib.abc.FileLoader` which can |
| 928 | import bytecode files (i.e. no source code files exist). |
| 929 | |
Marc-Andre Lemburg | 4fe29c9 | 2012-04-25 02:31:37 +0200 | [diff] [blame] | 930 | Please note that direct use of bytecode files (and thus not source code |
| 931 | files) inhibits your modules from being usable by all Python |
| 932 | implementations or new versions of Python which change the bytecode |
| 933 | format. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 934 | |
| 935 | .. versionadded:: 3.3 |
| 936 | |
| 937 | .. attribute:: name |
| 938 | |
| 939 | The name of the module the loader will handle. |
| 940 | |
| 941 | .. attribute:: path |
| 942 | |
| 943 | The path to the bytecode file. |
| 944 | |
| 945 | .. method:: is_package(fullname) |
| 946 | |
| 947 | Determines if the module is a package based on :attr:`path`. |
| 948 | |
| 949 | .. method:: get_code(fullname) |
| 950 | |
| 951 | Returns the code object for :attr:`name` created from :attr:`path`. |
| 952 | |
| 953 | .. method:: get_source(fullname) |
| 954 | |
| 955 | Returns ``None`` as bytecode files have no source when this loader is |
| 956 | used. |
| 957 | |
Brett Cannon | 062fcac | 2014-05-09 11:55:49 -0400 | [diff] [blame] | 958 | .. method:: load_module(name=None) |
| 959 | |
| 960 | Concrete implementation of :meth:`importlib.abc.Loader.load_module` where |
| 961 | specifying the name of the module to load is optional. |
| 962 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 963 | |
| 964 | .. class:: ExtensionFileLoader(fullname, path) |
| 965 | |
Eric Snow | 5179445 | 2013-10-03 12:08:55 -0600 | [diff] [blame] | 966 | A concrete implementation of :class:`importlib.abc.ExecutionLoader` for |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 967 | extension modules. |
| 968 | |
| 969 | The *fullname* argument specifies the name of the module the loader is to |
| 970 | support. The *path* argument is the path to the extension module's file. |
| 971 | |
| 972 | .. versionadded:: 3.3 |
| 973 | |
| 974 | .. attribute:: name |
| 975 | |
| 976 | Name of the module the loader supports. |
| 977 | |
| 978 | .. attribute:: path |
| 979 | |
| 980 | Path to the extension module. |
| 981 | |
Nick Coghlan | d5cacbb | 2015-05-23 22:24:10 +1000 | [diff] [blame] | 982 | .. method:: create_module(spec) |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 983 | |
Nick Coghlan | d5cacbb | 2015-05-23 22:24:10 +1000 | [diff] [blame] | 984 | Creates the module object from the given specification in accordance |
| 985 | with :pep:`489`. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 986 | |
Nick Coghlan | d5cacbb | 2015-05-23 22:24:10 +1000 | [diff] [blame] | 987 | .. versionadded:: 3.5 |
| 988 | |
| 989 | .. method:: exec_module(module) |
| 990 | |
| 991 | Initializes the given module object in accordance with :pep:`489`. |
| 992 | |
| 993 | .. versionadded:: 3.5 |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 994 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 995 | .. method:: is_package(fullname) |
| 996 | |
Brett Cannon | ac9f2f3 | 2012-08-10 13:47:54 -0400 | [diff] [blame] | 997 | Returns ``True`` if the file path points to a package's ``__init__`` |
| 998 | module based on :attr:`EXTENSION_SUFFIXES`. |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 999 | |
| 1000 | .. method:: get_code(fullname) |
| 1001 | |
| 1002 | Returns ``None`` as extension modules lack a code object. |
| 1003 | |
| 1004 | .. method:: get_source(fullname) |
| 1005 | |
| 1006 | Returns ``None`` as extension modules do not have source code. |
| 1007 | |
Eric Snow | 5179445 | 2013-10-03 12:08:55 -0600 | [diff] [blame] | 1008 | .. method:: get_filename(fullname) |
| 1009 | |
| 1010 | Returns :attr:`path`. |
| 1011 | |
Eric Snow | dcd01b4 | 2013-10-04 20:35:34 -0600 | [diff] [blame] | 1012 | .. versionadded:: 3.4 |
| 1013 | |
Brett Cannon | 938d44d | 2012-04-22 19:58:33 -0400 | [diff] [blame] | 1014 | |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 1015 | .. class:: ModuleSpec(name, loader, *, origin=None, loader_state=None, is_package=None) |
| 1016 | |
| 1017 | A specification for a module's import-system-related state. |
| 1018 | |
| 1019 | .. versionadded:: 3.4 |
| 1020 | |
| 1021 | .. attribute:: name |
| 1022 | |
| 1023 | (``__name__``) |
| 1024 | |
| 1025 | A string for the fully-qualified name of the module. |
| 1026 | |
| 1027 | .. attribute:: loader |
| 1028 | |
| 1029 | (``__loader__``) |
| 1030 | |
| 1031 | The loader to use for loading. For namespace packages this should be |
| 1032 | set to None. |
| 1033 | |
| 1034 | .. attribute:: origin |
| 1035 | |
| 1036 | (``__file__``) |
| 1037 | |
| 1038 | Name of the place from which the module is loaded, e.g. "builtin" for |
| 1039 | built-in modules and the filename for modules loaded from source. |
| 1040 | Normally "origin" should be set, but it may be None (the default) |
| 1041 | which indicates it is unspecified. |
| 1042 | |
| 1043 | .. attribute:: submodule_search_locations |
| 1044 | |
| 1045 | (``__path__``) |
| 1046 | |
| 1047 | List of strings for where to find submodules, if a package (None |
| 1048 | otherwise). |
| 1049 | |
| 1050 | .. attribute:: loader_state |
| 1051 | |
| 1052 | Container of extra module-specific data for use during loading (or |
| 1053 | None). |
| 1054 | |
| 1055 | .. attribute:: cached |
| 1056 | |
| 1057 | (``__cached__``) |
| 1058 | |
| 1059 | String for where the compiled module should be stored (or None). |
| 1060 | |
| 1061 | .. attribute:: parent |
| 1062 | |
| 1063 | (``__package__``) |
| 1064 | |
| 1065 | (Read-only) Fully-qualified name of the package to which the module |
| 1066 | belongs as a submodule (or None). |
| 1067 | |
| 1068 | .. attribute:: has_location |
| 1069 | |
Eric Snow | b282b3d | 2013-12-10 22:16:41 -0700 | [diff] [blame] | 1070 | Boolean indicating whether or not the module's "origin" |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 1071 | attribute refers to a loadable location. |
| 1072 | |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 1073 | :mod:`importlib.util` -- Utility code for importers |
| 1074 | --------------------------------------------------- |
| 1075 | |
| 1076 | .. module:: importlib.util |
Brett Cannon | 75321e8 | 2012-03-02 11:58:25 -0500 | [diff] [blame] | 1077 | :synopsis: Utility code for importers |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 1078 | |
| 1079 | This module contains the various objects that help in the construction of |
| 1080 | an :term:`importer`. |
| 1081 | |
Brett Cannon | 05a647d | 2013-06-14 19:02:34 -0400 | [diff] [blame] | 1082 | .. attribute:: MAGIC_NUMBER |
| 1083 | |
| 1084 | The bytes which represent the bytecode version number. If you need help with |
| 1085 | loading/writing bytecode then consider :class:`importlib.abc.SourceLoader`. |
| 1086 | |
| 1087 | .. versionadded:: 3.4 |
| 1088 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 1089 | .. function:: cache_from_source(path, debug_override=None, *, optimization=None) |
Brett Cannon | a3c9615 | 2013-06-14 22:26:30 -0400 | [diff] [blame] | 1090 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 1091 | Return the :pep:`3147`/:pep:`488` path to the byte-compiled file associated |
| 1092 | with the source *path*. For example, if *path* is ``/foo/bar/baz.py`` the return |
Brett Cannon | a3c9615 | 2013-06-14 22:26:30 -0400 | [diff] [blame] | 1093 | value would be ``/foo/bar/__pycache__/baz.cpython-32.pyc`` for Python 3.2. |
| 1094 | The ``cpython-32`` string comes from the current magic tag (see |
| 1095 | :func:`get_tag`; if :attr:`sys.implementation.cache_tag` is not defined then |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 1096 | :exc:`NotImplementedError` will be raised). |
Brett Cannon | a3c9615 | 2013-06-14 22:26:30 -0400 | [diff] [blame] | 1097 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 1098 | The *optimization* parameter is used to specify the optimization level of the |
| 1099 | bytecode file. An empty string represents no optimization, so |
| 1100 | ``/foo/bar/baz.py`` with an *optimization* of ``''`` will result in a |
| 1101 | bytecode path of ``/foo/bar/__pycache__/baz.cpython-32.pyc``. ``None`` causes |
| 1102 | the interpter's optimization level to be used. Any other value's string |
| 1103 | representation being used, so ``/foo/bar/baz.py`` with an *optimization* of |
| 1104 | ``2`` will lead to the bytecode path of |
| 1105 | ``/foo/bar/__pycache__/baz.cpython-32.opt-2.pyc``. The string representation |
| 1106 | of *optimization* can only be alphanumeric, else :exc:`ValueError` is raised. |
| 1107 | |
| 1108 | The *debug_override* parameter is deprecated and can be used to override |
| 1109 | the system's value for ``__debug__``. A ``True`` value is the equivalent of |
| 1110 | setting *optimization* to the empty string. A ``False`` value is the same as |
| 1111 | setting *optimization* to ``1``. If both *debug_override* an *optimization* |
| 1112 | are not ``None`` then :exc:`TypeError` is raised. |
Brett Cannon | a3c9615 | 2013-06-14 22:26:30 -0400 | [diff] [blame] | 1113 | |
| 1114 | .. versionadded:: 3.4 |
| 1115 | |
Brett Cannon | f299abd | 2015-04-13 14:21:02 -0400 | [diff] [blame] | 1116 | .. versionchanged ::3.5 |
| 1117 | The *optimization* parameter was added and the *debug_override* parameter |
| 1118 | was deprecated. |
| 1119 | |
Brett Cannon | a3c9615 | 2013-06-14 22:26:30 -0400 | [diff] [blame] | 1120 | |
| 1121 | .. function:: source_from_cache(path) |
| 1122 | |
| 1123 | Given the *path* to a :pep:`3147` file name, return the associated source code |
| 1124 | file path. For example, if *path* is |
| 1125 | ``/foo/bar/__pycache__/baz.cpython-32.pyc`` the returned path would be |
| 1126 | ``/foo/bar/baz.py``. *path* need not exist, however if it does not conform |
Larry Hastings | 770ce20 | 2015-04-19 13:50:12 -0700 | [diff] [blame] | 1127 | to :pep:`3147` or :pep:`488` format, a ``ValueError`` is raised. If |
Brett Cannon | a3c9615 | 2013-06-14 22:26:30 -0400 | [diff] [blame] | 1128 | :attr:`sys.implementation.cache_tag` is not defined, |
| 1129 | :exc:`NotImplementedError` is raised. |
| 1130 | |
| 1131 | .. versionadded:: 3.4 |
| 1132 | |
Brett Cannon | f24fecd | 2013-06-16 18:37:53 -0400 | [diff] [blame] | 1133 | .. function:: decode_source(source_bytes) |
| 1134 | |
| 1135 | Decode the given bytes representing source code and return it as a string |
| 1136 | with universal newlines (as required by |
| 1137 | :meth:`importlib.abc.InspectLoader.get_source`). |
| 1138 | |
| 1139 | .. versionadded:: 3.4 |
| 1140 | |
Brett Cannon | d200bf5 | 2012-05-13 13:45:09 -0400 | [diff] [blame] | 1141 | .. function:: resolve_name(name, package) |
| 1142 | |
| 1143 | Resolve a relative module name to an absolute one. |
| 1144 | |
| 1145 | If **name** has no leading dots, then **name** is simply returned. This |
| 1146 | allows for usage such as |
| 1147 | ``importlib.util.resolve_name('sys', __package__)`` without doing a |
| 1148 | check to see if the **package** argument is needed. |
| 1149 | |
| 1150 | :exc:`ValueError` is raised if **name** is a relative module name but |
| 1151 | package is a false value (e.g. ``None`` or the empty string). |
| 1152 | :exc:`ValueError` is also raised a relative name would escape its containing |
| 1153 | package (e.g. requesting ``..bacon`` from within the ``spam`` package). |
| 1154 | |
| 1155 | .. versionadded:: 3.3 |
| 1156 | |
Eric Snow | 6029e08 | 2014-01-25 15:32:46 -0700 | [diff] [blame] | 1157 | .. function:: find_spec(name, package=None) |
| 1158 | |
| 1159 | Find the :term:`spec <module spec>` for a module, optionally relative to |
| 1160 | the specified **package** name. If the module is in :attr:`sys.modules`, |
| 1161 | then ``sys.modules[name].__spec__`` is returned (unless the spec would be |
| 1162 | ``None`` or is not set, in which case :exc:`ValueError` is raised). |
| 1163 | Otherwise a search using :attr:`sys.meta_path` is done. ``None`` is |
| 1164 | returned if no spec is found. |
| 1165 | |
| 1166 | If **name** is for a submodule (contains a dot), the parent module is |
| 1167 | automatically imported. |
| 1168 | |
| 1169 | **name** and **package** work the same as for :func:`import_module`. |
| 1170 | |
| 1171 | .. versionadded:: 3.4 |
| 1172 | |
Brett Cannon | 2a17bde | 2014-05-30 14:55:29 -0400 | [diff] [blame] | 1173 | .. function:: module_from_spec(spec) |
| 1174 | |
Brett Cannon | 02d8454 | 2015-01-09 11:39:21 -0500 | [diff] [blame] | 1175 | Create a new module based on **spec** and ``spec.loader.create_module()``. |
Brett Cannon | 2a17bde | 2014-05-30 14:55:29 -0400 | [diff] [blame] | 1176 | |
Brett Cannon | 02d8454 | 2015-01-09 11:39:21 -0500 | [diff] [blame] | 1177 | If ``spec.loader.create_module()`` does not return ``None``, then any |
Brett Cannon | 2a17bde | 2014-05-30 14:55:29 -0400 | [diff] [blame] | 1178 | pre-existing attributes will not be reset. Also, no :exc:`AttributeError` |
| 1179 | will be raised if triggered while accessing **spec** or setting an attribute |
| 1180 | on the module. |
| 1181 | |
| 1182 | This function is preferred over using :class:`types.ModuleType` to create a |
| 1183 | new module as **spec** is used to set as many import-controlled attributes on |
| 1184 | the module as possible. |
| 1185 | |
| 1186 | .. versionadded:: 3.5 |
| 1187 | |
Georg Brandl | 8a1caa2 | 2010-07-29 16:01:11 +0000 | [diff] [blame] | 1188 | .. decorator:: module_for_loader |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 1189 | |
Brett Cannon | a22faca | 2013-05-28 17:50:14 -0400 | [diff] [blame] | 1190 | A :term:`decorator` for :meth:`importlib.abc.Loader.load_module` |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 1191 | to handle selecting the proper |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 1192 | module object to load with. The decorated method is expected to have a call |
Brett Cannon | 2a922ed | 2009-03-09 03:35:50 +0000 | [diff] [blame] | 1193 | signature taking two positional arguments |
| 1194 | (e.g. ``load_module(self, module)``) for which the second argument |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 1195 | will be the module **object** to be used by the loader. |
Brett Cannon | efad00d | 2012-04-27 17:27:14 -0400 | [diff] [blame] | 1196 | Note that the decorator will not work on static methods because of the |
| 1197 | assumption of two arguments. |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 1198 | |
Guido van Rossum | 0961354 | 2009-03-30 20:34:57 +0000 | [diff] [blame] | 1199 | The decorated method will take in the **name** of the module to be loaded |
| 1200 | as expected for a :term:`loader`. If the module is not found in |
Brett Cannon | 3dc48d6 | 2013-05-28 18:35:54 -0400 | [diff] [blame] | 1201 | :data:`sys.modules` then a new one is constructed. Regardless of where the |
| 1202 | module came from, :attr:`__loader__` set to **self** and :attr:`__package__` |
| 1203 | is set based on what :meth:`importlib.abc.InspectLoader.is_package` returns |
| 1204 | (if available). These attributes are set unconditionally to support |
| 1205 | reloading. |
Brett Cannon | efad00d | 2012-04-27 17:27:14 -0400 | [diff] [blame] | 1206 | |
| 1207 | If an exception is raised by the decorated method and a module was added to |
Brett Cannon | a87e31c | 2013-09-13 16:52:19 -0400 | [diff] [blame] | 1208 | :data:`sys.modules`, then the module will be removed to prevent a partially |
| 1209 | initialized module from being in left in :data:`sys.modules`. If the module |
| 1210 | was already in :data:`sys.modules` then it is left alone. |
Brett Cannon | d2e7b33 | 2009-02-17 02:45:03 +0000 | [diff] [blame] | 1211 | |
Brett Cannon | efad00d | 2012-04-27 17:27:14 -0400 | [diff] [blame] | 1212 | .. versionchanged:: 3.3 |
Georg Brandl | 61063cc | 2012-06-24 22:48:30 +0200 | [diff] [blame] | 1213 | :attr:`__loader__` and :attr:`__package__` are automatically set |
| 1214 | (when possible). |
Brett Cannon | 57b46f5 | 2009-03-02 14:38:26 +0000 | [diff] [blame] | 1215 | |
Brett Cannon | 3dc48d6 | 2013-05-28 18:35:54 -0400 | [diff] [blame] | 1216 | .. versionchanged:: 3.4 |
Brett Cannon | 0dbb4c7 | 2013-05-31 18:56:47 -0400 | [diff] [blame] | 1217 | Set :attr:`__name__`, :attr:`__loader__` :attr:`__package__` |
| 1218 | unconditionally to support reloading. |
| 1219 | |
| 1220 | .. deprecated:: 3.4 |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 1221 | The import machinery now directly performs all the functionality |
| 1222 | provided by this function. |
Brett Cannon | 3dc48d6 | 2013-05-28 18:35:54 -0400 | [diff] [blame] | 1223 | |
Georg Brandl | 8a1caa2 | 2010-07-29 16:01:11 +0000 | [diff] [blame] | 1224 | .. decorator:: set_loader |
Brett Cannon | 2cf03a8 | 2009-03-10 05:17:37 +0000 | [diff] [blame] | 1225 | |
Brett Cannon | a22faca | 2013-05-28 17:50:14 -0400 | [diff] [blame] | 1226 | A :term:`decorator` for :meth:`importlib.abc.Loader.load_module` |
| 1227 | to set the :attr:`__loader__` |
| 1228 | attribute on the returned module. If the attribute is already set the |
| 1229 | decorator does nothing. It is assumed that the first positional argument to |
| 1230 | the wrapped method (i.e. ``self``) is what :attr:`__loader__` should be set |
| 1231 | to. |
Brett Cannon | 2cf03a8 | 2009-03-10 05:17:37 +0000 | [diff] [blame] | 1232 | |
Brett Cannon | 4802bec | 2013-03-13 10:41:36 -0700 | [diff] [blame] | 1233 | .. versionchanged:: 3.4 |
Brett Cannon | 4c14b5d | 2013-05-04 13:56:58 -0400 | [diff] [blame] | 1234 | Set ``__loader__`` if set to ``None``, as if the attribute does not |
Brett Cannon | 4802bec | 2013-03-13 10:41:36 -0700 | [diff] [blame] | 1235 | exist. |
| 1236 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 1237 | .. deprecated:: 3.4 |
| 1238 | The import machinery takes care of this automatically. |
| 1239 | |
Georg Brandl | 8a1caa2 | 2010-07-29 16:01:11 +0000 | [diff] [blame] | 1240 | .. decorator:: set_package |
Brett Cannon | 57b46f5 | 2009-03-02 14:38:26 +0000 | [diff] [blame] | 1241 | |
Brett Cannon | a22faca | 2013-05-28 17:50:14 -0400 | [diff] [blame] | 1242 | A :term:`decorator` for :meth:`importlib.abc.Loader.load_module` to set the :attr:`__package__` attribute on the returned module. If :attr:`__package__` |
| 1243 | is set and has a value other than ``None`` it will not be changed. |
Brett Cannon | 16248a4 | 2009-04-01 20:47:14 +0000 | [diff] [blame] | 1244 | |
Eric Snow | ca2d854 | 2013-12-16 23:06:52 -0700 | [diff] [blame] | 1245 | .. deprecated:: 3.4 |
| 1246 | The import machinery takes care of this automatically. |
| 1247 | |
Eric Snow | b523f84 | 2013-11-22 09:05:39 -0700 | [diff] [blame] | 1248 | .. function:: spec_from_loader(name, loader, *, origin=None, is_package=None) |
| 1249 | |
| 1250 | A factory function for creating a :class:`ModuleSpec` instance based |
| 1251 | on a loader. The parameters have the same meaning as they do for |
| 1252 | ModuleSpec. The function uses available :term:`loader` APIs, such as |
| 1253 | :meth:`InspectLoader.is_package`, to fill in any missing |
| 1254 | information on the spec. |
| 1255 | |
| 1256 | .. versionadded:: 3.4 |
| 1257 | |
| 1258 | .. function:: spec_from_file_location(name, location, *, loader=None, submodule_search_locations=None) |
| 1259 | |
| 1260 | A factory function for creating a :class:`ModuleSpec` instance based |
| 1261 | on the path to a file. Missing information will be filled in on the |
| 1262 | spec by making use of loader APIs and by the implication that the |
| 1263 | module will be file-based. |
| 1264 | |
| 1265 | .. versionadded:: 3.4 |
Brett Cannon | a04dbe4 | 2014-04-04 13:53:38 -0400 | [diff] [blame] | 1266 | |
| 1267 | .. class:: LazyLoader(loader) |
| 1268 | |
| 1269 | A class which postpones the execution of the loader of a module until the |
| 1270 | module has an attribute accessed. |
| 1271 | |
| 1272 | This class **only** works with loaders that define |
Brett Cannon | 02d8454 | 2015-01-09 11:39:21 -0500 | [diff] [blame] | 1273 | :meth:`~importlib.abc.Loader.exec_module` as control over what module type |
| 1274 | is used for the module is required. For those same reasons, the loader's |
| 1275 | :meth:`~importlib.abc.Loader.create_module` method will be ignored (i.e., the |
| 1276 | loader's method should only return ``None``). Finally, |
Brett Cannon | a04dbe4 | 2014-04-04 13:53:38 -0400 | [diff] [blame] | 1277 | modules which substitute the object placed into :attr:`sys.modules` will |
| 1278 | not work as there is no way to properly replace the module references |
| 1279 | throughout the interpreter safely; :exc:`ValueError` is raised if such a |
| 1280 | substitution is detected. |
| 1281 | |
| 1282 | .. note:: |
| 1283 | For projects where startup time is critical, this class allows for |
| 1284 | potentially minimizing the cost of loading a module if it is never used. |
| 1285 | For projects where startup time is not essential then use of this class is |
| 1286 | **heavily** discouraged due to error messages created during loading being |
| 1287 | postponed and thus occurring out of context. |
| 1288 | |
| 1289 | .. versionadded:: 3.5 |
| 1290 | |
| 1291 | .. classmethod:: factory(loader) |
| 1292 | |
| 1293 | A static method which returns a callable that creates a lazy loader. This |
| 1294 | is meant to be used in situations where the loader is passed by class |
| 1295 | instead of by instance. |
| 1296 | :: |
| 1297 | |
| 1298 | suffixes = importlib.machinery.SOURCE_SUFFIXES |
| 1299 | loader = importlib.machinery.SourceFileLoader |
| 1300 | lazy_loader = importlib.util.LazyLoader.factory(loader) |
| 1301 | finder = importlib.machinery.FileFinder(path, [(lazy_loader, suffixes)]) |