Mercurial > cpython-lru_cache-weakref

annotate Lib/importlib/util.py @ 87690:66c1c9f32567 default tip

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Add use_weakref option to functools.lru_cache The use_weakref option makes lru_cache create weak references to the function arguments when creating the cache key, which prevents them from staying in the memory forever even after all other references to them are gone. This is a proof of concept for http://bugs.python.org/issue19859
author Radomir Dopieralski <devel@sheep.art.pl>
date Tue, 03 Dec 2013 16:02:48 +0100
parents 07229c6104b1
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 """Utility code for constructing importers, etc."""
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2
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3 from ._bootstrap import MAGIC_NUMBER
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4 from ._bootstrap import cache_from_source
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5 from ._bootstrap import decode_source
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6 from ._bootstrap import source_from_cache
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7 from ._bootstrap import spec_from_loader
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8 from ._bootstrap import spec_from_file_location
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9 from ._bootstrap import _resolve_name
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10
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11 from contextlib import contextmanager
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12 import functools
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13 import sys
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14 import warnings
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15
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16
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17 def resolve_name(name, package):
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18 """Resolve a relative module name to an absolute one."""
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19 if not name.startswith('.'):
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20 return name
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21 elif not package:
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22 raise ValueError('{!r} is not a relative name '
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23 '(no leading dot)'.format(name))
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24 level = 0
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25 for character in name:
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26 if character != '.':
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27 break
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28 level += 1
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29 return _resolve_name(name[level:], package, level)
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30
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31
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32 @contextmanager
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33 def _module_to_load(name):
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34 is_reload = name in sys.modules
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35
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36 module = sys.modules.get(name)
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37 if not is_reload:
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38 # This must be done before open() is called as the 'io' module
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39 # implicitly imports 'locale' and would otherwise trigger an
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40 # infinite loop.
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41 module = type(sys)(name)
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42 # This must be done before putting the module in sys.modules
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43 # (otherwise an optimization shortcut in import.c becomes wrong)
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44 module.__initializing__ = True
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45 sys.modules[name] = module
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46 try:
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47 yield module
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48 except Exception:
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49 if not is_reload:
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50 try:
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51 del sys.modules[name]
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52 except KeyError:
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53 pass
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54 finally:
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55 module.__initializing__ = False
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56
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57
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58 # XXX deprecate
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59 def set_package(fxn):
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60 """Set __package__ on the returned module."""
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61 @functools.wraps(fxn)
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62 def set_package_wrapper(*args, **kwargs):
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63 module = fxn(*args, **kwargs)
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64 if getattr(module, '__package__', None) is None:
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65 module.__package__ = module.__name__
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66 if not hasattr(module, '__path__'):
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67 module.__package__ = module.__package__.rpartition('.')[0]
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68 return module
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69 return set_package_wrapper
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70
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71
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72 # XXX deprecate
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73 def set_loader(fxn):
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74 """Set __loader__ on the returned module."""
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75 @functools.wraps(fxn)
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76 def set_loader_wrapper(self, *args, **kwargs):
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77 module = fxn(self, *args, **kwargs)
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78 if getattr(module, '__loader__', None) is None:
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79 module.__loader__ = self
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80 return module
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81 return set_loader_wrapper
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82
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83
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84 def module_for_loader(fxn):
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85 """Decorator to handle selecting the proper module for loaders.
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86
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87 The decorated function is passed the module to use instead of the module
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88 name. The module passed in to the function is either from sys.modules if
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89 it already exists or is a new module. If the module is new, then __name__
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90 is set the first argument to the method, __loader__ is set to self, and
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91 __package__ is set accordingly (if self.is_package() is defined) will be set
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92 before it is passed to the decorated function (if self.is_package() does
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93 not work for the module it will be set post-load).
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94
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95 If an exception is raised and the decorator created the module it is
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96 subsequently removed from sys.modules.
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97
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98 The decorator assumes that the decorated function takes the module name as
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99 the second argument.
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100
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101 """
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102 warnings.warn('The import system now takes care of this automatically.',
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103 PendingDeprecationWarning, stacklevel=2)
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104 @functools.wraps(fxn)
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105 def module_for_loader_wrapper(self, fullname, *args, **kwargs):
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106 with _module_to_load(fullname) as module:
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107 module.__loader__ = self
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108 try:
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109 is_package = self.is_package(fullname)
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110 except (ImportError, AttributeError):
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111 pass
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112 else:
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113 if is_package:
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114 module.__package__ = fullname
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115 else:
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116 module.__package__ = fullname.rpartition('.')[0]
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117 # If __package__ was not set above, __import__() will do it later.
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118 return fxn(self, module, *args, **kwargs)
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119
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120 return module_for_loader_wrapper