# HG changeset patch # User Yuya Nishihara <y...@tcha.org> # Date 1482155160 -32400 # Mon Dec 19 22:46:00 2016 +0900 # Branch stable # Node ID 09d785da911964c3282768438024a3b8e63dbd53 # Parent 7817df5585db1d87d3f6c7f496085c86d87e2e9a demandimport: do not raise ImportError for unknown item in fromlist
This is the behavior of the default __import__() function, which doesn't validate the existence of the fromlist items. Later on, the missing attribute is detected while processing the import statement. https://hg.python.org/cpython/file/v2.7.13/Python/import.c#l2575 The comtypes library relies on this (maybe) undocumented behavior, and we got a bug report to TortoiseHg, sigh. https://bitbucket.org/tortoisehg/thg/issues/4647/ The test added at 26a4e46af2bc verifies the behavior of the import statement, so this patch only adds the test of __import__() function and works around CPython/PyPy difference. diff --git a/mercurial/demandimport.py b/mercurial/demandimport.py --- a/mercurial/demandimport.py +++ b/mercurial/demandimport.py @@ -199,8 +199,11 @@ def _demandimport(name, globals=None, lo nonpkg = getattr(mod, '__path__', nothing) is nothing if symbol is nothing: if nonpkg: - # do not try relative import, which would raise ValueError - raise ImportError('cannot import name %s' % attr) + # do not try relative import, which would raise ValueError, + # and leave unknown attribute as the default __import__() + # would do. the missing attribute will be detected later + # while processing the import statement. + return mn = '%s.%s' % (mod.__name__, attr) if mn in ignore: importfunc = _origimport diff --git a/tests/test-demandimport.py b/tests/test-demandimport.py --- a/tests/test-demandimport.py +++ b/tests/test-demandimport.py @@ -70,7 +70,16 @@ try: print('no demandmod should be created for attribute of non-package ' 'module:\ncontextlib.unknownattr =', f(unknownattr)) except ImportError as inst: - print('contextlib.unknownattr = ImportError: %s' % inst) + print('contextlib.unknownattr = ImportError: %s' + % rsub(r"'", '', str(inst))) + +# Unlike the import statement, __import__() function should not raise +# ImportError even if fromlist has an unknown item +# (see Python/import.c:import_module_level() and ensure_fromlist()) +contextlibimp = __import__('contextlib', globals(), locals(), ['unknownattr']) +print("__import__('contextlib', ..., ['unknownattr']) =", f(contextlibimp)) +print("hasattr(contextlibimp, 'unknownattr') =", + util.safehasattr(contextlibimp, 'unknownattr')) demandimport.disable() os.environ['HGDEMANDIMPORT'] = 'disable' diff --git a/tests/test-demandimport.py.out b/tests/test-demandimport.py.out --- a/tests/test-demandimport.py.out +++ b/tests/test-demandimport.py.out @@ -18,4 +18,6 @@ re.stderr = <open file '<whatever>', mod re = <proxied module 'sys'> contextlib = <unloaded module 'contextlib'> contextlib.unknownattr = ImportError: cannot import name unknownattr +__import__('contextlib', ..., ['unknownattr']) = <module 'contextlib' from '?'> +hasattr(contextlibimp, 'unknownattr') = False node = <module 'mercurial.node' from '?'> _______________________________________________ Mercurial-devel mailing list Mercurial-devel@mercurial-scm.org https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
