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bpo-37444: Update differing exception between builtins and importlib (pythonGH-14869)
Imports now raise `TypeError` instead of `ValueError` for relative import failures. This makes things consistent between `builtins.__import__` and `importlib.__import__` as well as using a more natural import for the failure. https://bugs.python.org/issue37444 Automerge-Triggered-By: @brettcannon
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Lines changed: 134 additions & 108 deletions

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‎Doc/library/importlib.rst‎

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@@ -1433,13 +1433,18 @@ an :term:`importer`.
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``importlib.util.resolve_name('sys', __package__)`` without doing a
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check to see if the **package** argument is needed.
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:exc:`ValueError` is raised if **name** is a relative module name but
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package is a false value (e.g. ``None`` or the empty string).
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:exc:`ValueError` is also raised a relative name would escape its containing
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:exc:`ImportError` is raised if **name** is a relative module name but
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**package** is a false value (e.g. ``None`` or the empty string).
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:exc:`ImportError` is also raised a relative name would escape its containing
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package (e.g. requesting ``..bacon`` from within the ``spam`` package).
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.. versionadded:: 3.3
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.. versionchanged:: 3.9
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To improve consistency with import statements, raise
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:exc:`ImportError` instead of :exc:`ValueError` for invalid relative
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import attempts.
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.. function:: find_spec(name, package=None)
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Find the :term:`spec <module spec>` for a module, optionally relative to

‎Doc/whatsnew/3.9.rst‎

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@@ -75,6 +75,12 @@ New Features
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Other Language Changes
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======================
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* :func:`builtins.__import__` now raises :exc:`ImportError` instead of
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:exc:`ValueError` as used to occur when a relative import went past
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its top-level package.
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(Contributed by Ngalim Siregar in :issue:`37444`.)
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* Python now gets the absolute path of the script filename specified on
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the command line (ex: ``python3 script.py``): the ``__file__`` attribute of
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the ``__main__`` module, ``sys.argv[0]`` and ``sys.path[0]`` become an
@@ -118,6 +124,13 @@ pprint
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:mod:`pprint` can now pretty-print :class:`types.SimpleNamespace`.
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(Contributed by Carl Bordum Hansen in :issue:`37376`.)
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importlib
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---------
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To improve consistency with import statements, :func:`importlib.util.resolve_name`
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now raises :exc:`ImportError` instead of :exc:`ValueError` for invalid relative
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import attempts.
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(Contributed by Ngalim Siregar in :issue:`37444`.)
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Optimizations
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=============
@@ -180,4 +193,11 @@ Porting to Python 3.9
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This section lists previously described changes and other bugfixes
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that may require changes to your code.
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Changes in the Python API
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-------------------------
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* :func:`builtins.__import__` and :func:`importlib.util.resolve_name` now raise
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:exc:`ImportError` where it previously raised :exc:`ValueError`. Callers
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catching the specific exception type and supporting both Python 3.9 and
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earlier versions will need to catch both:
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``except (ImportError, ValueError):``

‎Lib/importlib/_bootstrap.py‎

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Original file line numberDiff line numberDiff line change
@@ -873,7 +873,7 @@ def _resolve_name(name, package, level):
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"""Resolve a relative module name to an absolute one."""
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bits = package.rsplit('.', level - 1)
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if len(bits) < level:
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raise ValueError('attempted relative import beyond top-level package')
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raise ImportError('attempted relative import beyond top-level package')
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base = bits[0]
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return '{}.{}'.format(base, name) if name else base
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‎Lib/importlib/util.py‎

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Original file line numberDiff line numberDiff line change
@@ -29,8 +29,8 @@ def resolve_name(name, package):
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if not name.startswith('.'):
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return name
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elif not package:
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raise ValueError(f'no package specified for {repr(name)} '
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'(required for relative module names)')
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raise ImportError(f'no package specified for {repr(name)} '
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'(required for relative module names)')
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level = 0
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for character in name:
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if character != '.':

‎Lib/test/test_importlib/import_/test_relative_imports.py‎

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@@ -156,7 +156,7 @@ def test_too_high_from_package(self):
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{'__name__': 'pkg', '__path__': ['blah']})
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def callback(global_):
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self.__import__('pkg')
159-
with self.assertRaises(ValueError):
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with self.assertRaises(ImportError):
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self.__import__('', global_, fromlist=['top_level'],
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level=2)
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self.relative_import_test(create, globals_, callback)
@@ -167,7 +167,7 @@ def test_too_high_from_module(self):
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globals_ = {'__package__': 'pkg'}, {'__name__': 'pkg.module'}
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def callback(global_):
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self.__import__('pkg')
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with self.assertRaises(ValueError):
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with self.assertRaises(ImportError):
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self.__import__('', global_, fromlist=['top_level'],
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level=2)
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self.relative_import_test(create, globals_, callback)

‎Lib/test/test_importlib/test_util.py‎

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@@ -375,7 +375,7 @@ def test_absolute_within_package(self):
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376376
def test_no_package(self):
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# .bacon in ''
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with self.assertRaises(ValueError):
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with self.assertRaises(ImportError):
379379
self.util.resolve_name('.bacon', '')
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def test_in_package(self):
@@ -390,7 +390,7 @@ def test_other_package(self):
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391391
def test_escape(self):
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# ..bacon in spam
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with self.assertRaises(ValueError):
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with self.assertRaises(ImportError):
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self.util.resolve_name('..bacon', 'spam')
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@@ -518,7 +518,7 @@ def test_find_relative_module_missing_package(self):
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with util.temp_module(name, pkg=True) as pkg_dir:
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fullname, _ = util.submodule(name, subname, pkg_dir)
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relname = '.' + subname
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with self.assertRaises(ValueError):
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with self.assertRaises(ImportError):
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self.util.find_spec(relname)
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self.assertNotIn(name, sorted(sys.modules))
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self.assertNotIn(fullname, sorted(sys.modules))

‎Misc/NEWS.d/next/Core and Builtins/2019-07-20-22-34-42.bpo-37444.UOd3Xs.rst‎

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@@ -0,0 +1 @@
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Update differing exception between :meth:`builtins.__import__` and :meth:`importlib.__import__`.

‎Python/import.c‎

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@@ -1671,7 +1671,7 @@ resolve_name(PyThreadState *tstate, PyObject *name, PyObject *globals, int level
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goto error;
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}
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else if (last_dot == -1) {
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_PyErr_SetString(tstate, PyExc_ValueError,
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_PyErr_SetString(tstate, PyExc_ImportError,
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"attempted relative import beyond top-level "
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"package");
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goto error;

‎Python/importlib.h‎

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