| 4710c53d |
1 | """Faux ``threading`` version using ``dummy_thread`` instead of ``thread``.\r |
| 2 | \r |
| 3 | The module ``_dummy_threading`` is added to ``sys.modules`` in order\r |
| 4 | to not have ``threading`` considered imported. Had ``threading`` been\r |
| 5 | directly imported it would have made all subsequent imports succeed\r |
| 6 | regardless of whether ``thread`` was available which is not desired.\r |
| 7 | \r |
| 8 | """\r |
| 9 | from sys import modules as sys_modules\r |
| 10 | \r |
| 11 | import dummy_thread\r |
| 12 | \r |
| 13 | # Declaring now so as to not have to nest ``try``s to get proper clean-up.\r |
| 14 | holding_thread = False\r |
| 15 | holding_threading = False\r |
| 16 | holding__threading_local = False\r |
| 17 | \r |
| 18 | try:\r |
| 19 | # Could have checked if ``thread`` was not in sys.modules and gone\r |
| 20 | # a different route, but decided to mirror technique used with\r |
| 21 | # ``threading`` below.\r |
| 22 | if 'thread' in sys_modules:\r |
| 23 | held_thread = sys_modules['thread']\r |
| 24 | holding_thread = True\r |
| 25 | # Must have some module named ``thread`` that implements its API\r |
| 26 | # in order to initially import ``threading``.\r |
| 27 | sys_modules['thread'] = sys_modules['dummy_thread']\r |
| 28 | \r |
| 29 | if 'threading' in sys_modules:\r |
| 30 | # If ``threading`` is already imported, might as well prevent\r |
| 31 | # trying to import it more than needed by saving it if it is\r |
| 32 | # already imported before deleting it.\r |
| 33 | held_threading = sys_modules['threading']\r |
| 34 | holding_threading = True\r |
| 35 | del sys_modules['threading']\r |
| 36 | \r |
| 37 | if '_threading_local' in sys_modules:\r |
| 38 | # If ``_threading_local`` is already imported, might as well prevent\r |
| 39 | # trying to import it more than needed by saving it if it is\r |
| 40 | # already imported before deleting it.\r |
| 41 | held__threading_local = sys_modules['_threading_local']\r |
| 42 | holding__threading_local = True\r |
| 43 | del sys_modules['_threading_local']\r |
| 44 | \r |
| 45 | import threading\r |
| 46 | # Need a copy of the code kept somewhere...\r |
| 47 | sys_modules['_dummy_threading'] = sys_modules['threading']\r |
| 48 | del sys_modules['threading']\r |
| 49 | sys_modules['_dummy__threading_local'] = sys_modules['_threading_local']\r |
| 50 | del sys_modules['_threading_local']\r |
| 51 | from _dummy_threading import *\r |
| 52 | from _dummy_threading import __all__\r |
| 53 | \r |
| 54 | finally:\r |
| 55 | # Put back ``threading`` if we overwrote earlier\r |
| 56 | \r |
| 57 | if holding_threading:\r |
| 58 | sys_modules['threading'] = held_threading\r |
| 59 | del held_threading\r |
| 60 | del holding_threading\r |
| 61 | \r |
| 62 | # Put back ``_threading_local`` if we overwrote earlier\r |
| 63 | \r |
| 64 | if holding__threading_local:\r |
| 65 | sys_modules['_threading_local'] = held__threading_local\r |
| 66 | del held__threading_local\r |
| 67 | del holding__threading_local\r |
| 68 | \r |
| 69 | # Put back ``thread`` if we overwrote, else del the entry we made\r |
| 70 | if holding_thread:\r |
| 71 | sys_modules['thread'] = held_thread\r |
| 72 | del held_thread\r |
| 73 | else:\r |
| 74 | del sys_modules['thread']\r |
| 75 | del holding_thread\r |
| 76 | \r |
| 77 | del dummy_thread\r |
| 78 | del sys_modules\r |
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