bpo-32225: Implementation of PEP 562 (#4731) · pythoncapi/cpython@5364b5c · GitHub
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bpo-32225: Implementation of PEP 562 (python#4731)
Implement PEP 562: module __getattr__ and __dir__. The implementation simply updates module_getattro and module_dir.
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‎Doc/reference/datamodel.rst‎

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‎Doc/whatsnew/3.7.rst‎

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PEP written by Erik M. Bray; implementation by Masayuki Yamamoto.
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PEP 562: Customization of access to module attributes
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-----------------------------------------------------
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It is sometimes convenient to customize or otherwise have control over access
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to module attributes. A typical example is managing deprecation warnings.
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Typical workarounds are assigning ``__class__`` of a module object to
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a custom subclass of :class:`types.ModuleType` or replacing the ``sys.modules``
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item with a custom wrapper instance. This procedure is now simplified by
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recognizing ``__getattr__`` defined directly in a module that would act like
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a normal ``__getattr__`` method, except that it will be defined on module
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*instances*.
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.. seealso::
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:pep:`562` -- Module ``__getattr__`` and ``__dir__``
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PEP written and implemented by Ivan Levkivskyi
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PEP 564: Add new time functions with nanosecond resolution
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----------------------------------------------------------
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‎Lib/test/bad_getattr.py‎

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x = 1
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__getattr__ = "Surprise!"
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__dir__ = "Surprise again!"

‎Lib/test/bad_getattr2.py‎

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def __getattr__():
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"Bad one"
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x = 1
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def __dir__(bad_sig):
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return []

‎Lib/test/bad_getattr3.py‎

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def __getattr__(name):
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if name != 'delgetattr':
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raise AttributeError
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del globals()['__getattr__']
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raise AttributeError

‎Lib/test/good_getattr.py‎

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x = 1
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def __dir__():
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return ['a', 'b', 'c']
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def __getattr__(name):
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if name == "yolo":
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raise AttributeError("Deprecated, use whatever instead")
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return f"There is {name}"
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y = 2

‎Lib/test/test_module.py‎

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gc_collect()
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self.assertIs(wr(), None)
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def test_module_getattr(self):
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import test.good_getattr as gga
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from test.good_getattr import test
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self.assertEqual(test, "There is test")
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self.assertEqual(gga.x, 1)
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self.assertEqual(gga.y, 2)
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with self.assertRaisesRegex(AttributeError,
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"Deprecated, use whatever instead"):
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gga.yolo
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self.assertEqual(gga.whatever, "There is whatever")
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del sys.modules['test.good_getattr']
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def test_module_getattr_errors(self):
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import test.bad_getattr as bga
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from test import bad_getattr2
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self.assertEqual(bga.x, 1)
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self.assertEqual(bad_getattr2.x, 1)
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with self.assertRaises(TypeError):
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bga.nope
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with self.assertRaises(TypeError):
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bad_getattr2.nope
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del sys.modules['test.bad_getattr']
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if 'test.bad_getattr2' in sys.modules:
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del sys.modules['test.bad_getattr2']
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def test_module_dir(self):
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import test.good_getattr as gga
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self.assertEqual(dir(gga), ['a', 'b', 'c'])
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del sys.modules['test.good_getattr']
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def test_module_dir_errors(self):
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import test.bad_getattr as bga
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from test import bad_getattr2
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with self.assertRaises(TypeError):
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dir(bga)
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with self.assertRaises(TypeError):
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dir(bad_getattr2)
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del sys.modules['test.bad_getattr']
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if 'test.bad_getattr2' in sys.modules:
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del sys.modules['test.bad_getattr2']
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def test_module_getattr_tricky(self):
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from test import bad_getattr3
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# these lookups should not crash
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with self.assertRaises(AttributeError):
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bad_getattr3.one
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with self.assertRaises(AttributeError):
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bad_getattr3.delgetattr
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if 'test.bad_getattr3' in sys.modules:
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del sys.modules['test.bad_getattr3']
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def test_module_repr_minimal(self):
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# reprs when modules have no __file__, __name__, or __loader__
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m = ModuleType('foo')

‎Misc/NEWS.d/next/Core and Builtins/2017-12-05-21-33-47.bpo-32225.ucKjvw.rst‎

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PEP 562: Add support for module ``__getattr__`` and ``__dir__``. Implemented by Ivan
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Levkivskyi.

‎Objects/moduleobject.c‎

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