Get rid of _once(); inlining it takes less code. :-)
Also, don't call gettempdir() in the default expression for the 'dir' argument to various functions; use 'dir=None' for the default and insert 'if dir is None: dir = gettemptir()' in the bodies. That way the work done by gettempdir is postponed until needed.
This commit is contained in:
Guido van Rossum
parent
787410680b
commit
e888cdc683
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@ -80,33 +80,6 @@ tempdir = None
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_once_lock = _allocate_lock()
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def _once(var, initializer):
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"""Wrapper to execute an initialization operation just once,
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even if multiple threads reach the same point at the same time.
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var is the name (as a string) of the variable to be entered into
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the current global namespace.
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initializer is a callable which will return the appropriate initial
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value for variable. It will be called only if variable is not
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present in the global namespace, or its current value is None.
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Do not call _once from inside an initializer routine, it will deadlock.
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"""
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vars = globals()
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# Check first outside the lock.
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if vars.get(var) is not None:
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return
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try:
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_once_lock.acquire()
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# Check again inside the lock.
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if vars.get(var) is not None:
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return
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vars[var] = initializer()
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finally:
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_once_lock.release()
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class _RandomNameSequence:
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"""An instance of _RandomNameSequence generates an endless
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sequence of unpredictable strings which can safely be incorporated
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@ -178,8 +151,7 @@ def _candidate_tempdir_list():
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def _get_default_tempdir():
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"""Calculate the default directory to use for temporary files.
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This routine should be called through '_once' (see above) as we
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do not want multiple threads attempting this calculation simultaneously.
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This routine should be called exactly once.
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We determine whether or not a candidate temp dir is usable by
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trying to create and write to a file in that directory. If this
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@ -212,10 +184,19 @@ def _get_default_tempdir():
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raise IOError, (_errno.ENOENT,
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("No usable temporary directory found in %s" % dirlist))
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_name_sequence = None
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def _get_candidate_names():
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"""Common setup sequence for all user-callable interfaces."""
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_once('_name_sequence', _RandomNameSequence)
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global _name_sequence
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if _name_sequence is None:
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_once_lock.acquire()
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try:
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if _name_sequence is None:
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_name_sequence = _RandomNameSequence()
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finally:
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_once_lock.release()
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return _name_sequence
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@ -245,12 +226,21 @@ def gettempprefix():
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"""Accessor for tempdir.template."""
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return template
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tempdir = None
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def gettempdir():
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"""Accessor for tempdir.tempdir."""
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_once('tempdir', _get_default_tempdir)
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global tempdir
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if tempdir is None:
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_once_lock.acquire()
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try:
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if tempdir is None:
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tempdir = _get_default_tempdir()
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finally:
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_once_lock.release()
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return tempdir
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def mkstemp(suffix="", prefix=template, dir=gettempdir(), text=False):
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def mkstemp(suffix="", prefix=template, dir=None, text=False):
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"""mkstemp([suffix, [prefix, [dir, [text]]]])
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User-callable function to create and return a unique temporary
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file. The return value is a pair (fd, name) where fd is the
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@ -277,6 +267,9 @@ def mkstemp(suffix="", prefix=template, dir=gettempdir(), text=False):
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Caller is responsible for deleting the file when done with it.
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"""
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if dir is None:
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dir = gettempdir()
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if text:
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flags = _text_openflags
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else:
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@ -285,7 +278,7 @@ def mkstemp(suffix="", prefix=template, dir=gettempdir(), text=False):
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return _mkstemp_inner(dir, prefix, suffix, flags)
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def mkdtemp(suffix="", prefix=template, dir=gettempdir()):
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def mkdtemp(suffix="", prefix=template, dir=None):
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"""mkdtemp([suffix, [prefix, [dir]]])
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User-callable function to create and return a unique temporary
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directory. The return value is the pathname of the directory.
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@ -299,6 +292,9 @@ def mkdtemp(suffix="", prefix=template, dir=gettempdir()):
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Caller is responsible for deleting the directory when done with it.
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"""
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if dir is None:
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dir = gettempdir()
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names = _get_candidate_names()
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for seq in xrange(TMP_MAX):
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@ -314,7 +310,7 @@ def mkdtemp(suffix="", prefix=template, dir=gettempdir()):
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raise IOError, (_errno.EEXIST, "No usable temporary directory name found")
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def mktemp(suffix="", prefix=template, dir=gettempdir()):
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def mktemp(suffix="", prefix=template, dir=None):
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"""mktemp([suffix, [prefix, [dir]]])
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User-callable function to return a unique temporary file name. The
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file is not created.
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@ -332,6 +328,9 @@ def mktemp(suffix="", prefix=template, dir=gettempdir()):
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_warn("mktemp is a potential security risk to your program",
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RuntimeWarning, stacklevel=2)
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if dir is None:
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dir = gettempdir()
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names = _get_candidate_names()
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for seq in xrange(TMP_MAX):
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name = names.next()
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@ -383,7 +382,7 @@ class _TemporaryFileWrapper:
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self.close()
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def NamedTemporaryFile(mode='w+b', bufsize=-1, suffix="",
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prefix=template, dir=gettempdir()):
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prefix=template, dir=None):
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"""Create and return a temporary file.
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Arguments:
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'prefix', 'suffix', 'dir' -- as for mkstemp.
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@ -396,6 +395,9 @@ def NamedTemporaryFile(mode='w+b', bufsize=-1, suffix="",
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closed.
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"""
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if dir is None:
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dir = gettempdir()
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if 'b' in mode:
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flags = _bin_openflags
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else:
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@ -417,7 +419,7 @@ if _os.name != 'posix' or _os.sys.platform == 'cygwin':
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else:
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def TemporaryFile(mode='w+b', bufsize=-1, suffix="",
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prefix=template, dir=gettempdir()):
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prefix=template, dir=None):
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"""Create and return a temporary file.
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Arguments:
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'prefix', 'suffix', 'directory' -- as for mkstemp.
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@ -429,6 +431,9 @@ else:
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exist when it is closed.
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"""
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if dir is None:
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dir = gettempdir()
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if 'b' in mode:
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flags = _bin_openflags
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else:
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@ -84,67 +84,6 @@ class test_exports(TC):
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test_classes.append(test_exports)
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class test__once(TC):
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"""Test the internal function _once."""
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def setUp(self):
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tempfile.once_var = None
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self.already_called = 0
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def tearDown(self):
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del tempfile.once_var
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def callMeOnce(self):
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self.failIf(self.already_called, "callMeOnce called twice")
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self.already_called = 1
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return 24
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def do_once(self):
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tempfile._once('once_var', self.callMeOnce)
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def test_once_initializes(self):
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"""_once initializes its argument"""
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self.do_once()
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self.assertEqual(tempfile.once_var, 24,
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"once_var=%d, not 24" % tempfile.once_var)
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self.assertEqual(self.already_called, 1,
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"already_called=%d, not 1" % self.already_called)
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def test_once_means_once(self):
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"""_once calls the callback just once"""
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self.do_once()
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self.do_once()
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self.do_once()
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self.do_once()
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def test_once_namespace_safe(self):
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"""_once does not modify anything but its argument"""
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env_copy = tempfile.__dict__.copy()
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self.do_once()
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env = tempfile.__dict__
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a = env.keys()
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a.sort()
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b = env_copy.keys()
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b.sort()
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self.failIf(len(a) != len(b))
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for i in xrange(len(a)):
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self.failIf(a[i] != b[i])
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key = a[i]
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if key != 'once_var':
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self.failIf(env[key] != env_copy[key])
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test_classes.append(test__once)
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class test__RandomNameSequence(TC):
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"""Test the internal iterator object _RandomNameSequence."""
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