Update of /cvsroot/python/python/dist/src/Lib
In directory sc8-pr-cvs1:/tmp/cvs-serv13682/Lib
Added Files:
dummy_thread.py dummy_threading.py
Log Message:
Brett Cannon's dummy_thread and dummy_threading modules (SF patch
622537), with some nitpicking editorial changes.
--- NEW FILE: dummy_thread.py ---
"""Drop-in replacement for the thread module.
Meant to be used as a brain-dead substitute so that threaded code does
not need to be rewritten for when the thread module is not present.
Suggested usage is::
try:
import thread
except ImportError:
import dummy_thread as thread
"""
__author__ = "Brett Cannon"
__email__ = "brett@python.org"
# Exports only things specified by thread documentation
# (skipping obsolete synonyms allocate(), start_new(), exit_thread())
__all__ = ['error', 'start_new_thread', 'exit', 'get_ident', 'allocate_lock',
'LockType']
import traceback as _traceback
class error(Exception):
"""Dummy implementation of thread.error."""
def __init__(self, *args):
self.args = args
def start_new_thread(function, args, kwargs={}):
"""Dummy implementation of thread.start_new_thread().
Compatibility is maintained by making sure that ``args`` is a
tuple and ``kwargs`` is a dictionary. If an exception is raised
and it is SystemExit (which can be done by thread.exit()) it is
caught and nothing is done; all other exceptions are printed out
by using traceback.print_exc().
"""
if type(args) != type(tuple()):
raise TypeError("2nd arg must be a tuple")
if type(kwargs) != type(dict()):
raise TypeError("3rd arg must be a dict")
try:
function(*args, **kwargs)
except SystemExit:
pass
except:
_traceback.print_exc()
def exit():
"""Dummy implementation of thread.exit()."""
raise SystemExit
def get_ident():
"""Dummy implementation of thread.get_ident().
Since this module should only be used when threadmodule is not
available, it is safe to assume that the current process is the
only thread. Thus a constant can be safely returned.
"""
return -1
def allocate_lock():
"""Dummy implementation of thread.allocate_lock()."""
return LockType()
class LockType(object):
"""Class implementing dummy implementation of thread.LockType.
Compatibility is maintained by maintaining self.locked_status
which is a boolean that stores the state of the lock. Pickling of
the lock, though, should not be done since if the thread module is
then used with an unpickled ``lock()`` from here problems could
occur from this class not having atomic methods.
"""
def __init__(self):
self.locked_status = False
def acquire(self, waitflag=None):
"""Dummy implementation of acquire().
For blocking calls, self.locked_status is automatically set to
True and returned appropriately based on value of
``waitflag``. If it is non-blocking, then the value is
actually checked and not set if it is already acquired. This
is all done so that threading.Condition's assert statements
aren't triggered and throw a little fit.
"""
if waitflag is None:
self.locked_status = True
return None
elif not waitflag:
if not self.locked_status:
self.locked_status = True
return True
else:
return False
else:
self.locked_status = True
return True
def release(self):
"""Release the dummy lock."""
# XXX Perhaps shouldn't actually bother to test? Could lead
# to problems for complex, threaded code.
if not self.locked_status:
raise error
self.locked_status = False
return True
def locked(self):
return self.locked_status
--- NEW FILE: dummy_threading.py ---
"""Faux ``threading`` version using ``dummy_thread`` instead of ``thread``.
The module ``_dummy_threading`` is added to ``sys.modules`` in order
to not have ``threading`` considered imported. Had ``threading`` been
directly imported it would have made all subsequent imports succeed
regardless of whether ``thread`` was available which is not desired.
:Author: Brett Cannon
:Contact: brett@python.org
XXX: Try to get rid of ``_dummy_threading``.
"""
from sys import modules as sys_modules
import dummy_thread
# Declaring now so as to not have to nest ``try``s to get proper clean-up.
holding_thread = False
holding_threading = False
try:
# Could have checked if ``thread`` was not in sys.modules and gone
# a different route, but decided to mirror technique used with
# ``threading`` below.
if 'thread' in sys_modules:
held_thread = sys_modules['thread']
holding_thread = True
# Must have some module named ``thread`` that implements its API
# in order to initially import ``threading``.
sys_modules['thread'] = sys_modules['dummy_thread']
if 'threading' in sys_modules:
# If ``threading`` is already imported, might as well prevent
# trying to import it more than needed by saving it if it is
# already imported before deleting it.
held_threading = sys_modules['threading']
holding_threading = True
del sys_modules['threading']
import threading
# Need a copy of the code kept somewhere...
sys_modules['_dummy_threading'] = sys_modules['threading']
del sys_modules['threading']
from _dummy_threading import *
from _dummy_threading import __all__
finally:
# Put back ``threading`` if we overwrote earlier
if holding_threading:
sys_modules['threading'] = held_threading
del held_threading
del holding_threading
# Put back ``thread`` if we overwrote, else del the entry we made
if holding_thread:
sys_modules['thread'] = held_thread
del held_thread
else:
del sys_modules['thread']
del holding_thread
del dummy_thread
del sys_modules
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