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annotate lib/python3.8/site-packages/pip/_vendor/contextlib2.py @ 0:9e54283cc701 draft

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"planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
author guerler
date Mon, 27 Jul 2020 03:47:31 -0400
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1 """contextlib2 - backports and enhancements to the contextlib module"""
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2
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3 import abc
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4 import sys
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5 import warnings
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6 from collections import deque
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7 from functools import wraps
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8
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9 __all__ = ["contextmanager", "closing", "nullcontext",
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10 "AbstractContextManager",
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11 "ContextDecorator", "ExitStack",
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12 "redirect_stdout", "redirect_stderr", "suppress"]
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13
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14 # Backwards compatibility
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15 __all__ += ["ContextStack"]
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16
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17
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18 # Backport abc.ABC
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19 if sys.version_info[:2] >= (3, 4):
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20 _abc_ABC = abc.ABC
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21 else:
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22 _abc_ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()})
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23
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24
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25 # Backport classic class MRO
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26 def _classic_mro(C, result):
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27 if C in result:
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28 return
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29 result.append(C)
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30 for B in C.__bases__:
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31 _classic_mro(B, result)
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32 return result
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33
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34
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35 # Backport _collections_abc._check_methods
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36 def _check_methods(C, *methods):
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37 try:
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38 mro = C.__mro__
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39 except AttributeError:
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40 mro = tuple(_classic_mro(C, []))
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41
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42 for method in methods:
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43 for B in mro:
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44 if method in B.__dict__:
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45 if B.__dict__[method] is None:
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46 return NotImplemented
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47 break
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48 else:
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49 return NotImplemented
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50 return True
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51
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52
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53 class AbstractContextManager(_abc_ABC):
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54 """An abstract base class for context managers."""
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55
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56 def __enter__(self):
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57 """Return `self` upon entering the runtime context."""
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58 return self
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59
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60 @abc.abstractmethod
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61 def __exit__(self, exc_type, exc_value, traceback):
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62 """Raise any exception triggered within the runtime context."""
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63 return None
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64
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65 @classmethod
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66 def __subclasshook__(cls, C):
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67 """Check whether subclass is considered a subclass of this ABC."""
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68 if cls is AbstractContextManager:
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69 return _check_methods(C, "__enter__", "__exit__")
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70 return NotImplemented
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71
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72
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73 class ContextDecorator(object):
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74 """A base class or mixin that enables context managers to work as decorators."""
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75
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76 def refresh_cm(self):
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77 """Returns the context manager used to actually wrap the call to the
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78 decorated function.
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79
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80 The default implementation just returns *self*.
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81
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82 Overriding this method allows otherwise one-shot context managers
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83 like _GeneratorContextManager to support use as decorators via
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84 implicit recreation.
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85
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86 DEPRECATED: refresh_cm was never added to the standard library's
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87 ContextDecorator API
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88 """
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89 warnings.warn("refresh_cm was never added to the standard library",
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90 DeprecationWarning)
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91 return self._recreate_cm()
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92
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93 def _recreate_cm(self):
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94 """Return a recreated instance of self.
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95
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96 Allows an otherwise one-shot context manager like
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97 _GeneratorContextManager to support use as
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98 a decorator via implicit recreation.
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99
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100 This is a private interface just for _GeneratorContextManager.
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101 See issue #11647 for details.
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102 """
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103 return self
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104
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105 def __call__(self, func):
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106 @wraps(func)
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107 def inner(*args, **kwds):
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108 with self._recreate_cm():
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109 return func(*args, **kwds)
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110 return inner
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111
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112
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113 class _GeneratorContextManager(ContextDecorator):
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114 """Helper for @contextmanager decorator."""
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115
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116 def __init__(self, func, args, kwds):
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117 self.gen = func(*args, **kwds)
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118 self.func, self.args, self.kwds = func, args, kwds
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119 # Issue 19330: ensure context manager instances have good docstrings
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120 doc = getattr(func, "__doc__", None)
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121 if doc is None:
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122 doc = type(self).__doc__
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123 self.__doc__ = doc
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124 # Unfortunately, this still doesn't provide good help output when
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125 # inspecting the created context manager instances, since pydoc
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126 # currently bypasses the instance docstring and shows the docstring
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127 # for the class instead.
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128 # See http://bugs.python.org/issue19404 for more details.
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129
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130 def _recreate_cm(self):
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131 # _GCM instances are one-shot context managers, so the
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132 # CM must be recreated each time a decorated function is
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133 # called
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134 return self.__class__(self.func, self.args, self.kwds)
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135
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136 def __enter__(self):
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137 try:
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138 return next(self.gen)
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139 except StopIteration:
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140 raise RuntimeError("generator didn't yield")
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141
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142 def __exit__(self, type, value, traceback):
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143 if type is None:
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144 try:
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145 next(self.gen)
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146 except StopIteration:
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147 return
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148 else:
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149 raise RuntimeError("generator didn't stop")
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150 else:
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151 if value is None:
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152 # Need to force instantiation so we can reliably
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153 # tell if we get the same exception back
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154 value = type()
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155 try:
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156 self.gen.throw(type, value, traceback)
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157 raise RuntimeError("generator didn't stop after throw()")
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158 except StopIteration as exc:
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159 # Suppress StopIteration *unless* it's the same exception that
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160 # was passed to throw(). This prevents a StopIteration
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161 # raised inside the "with" statement from being suppressed.
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162 return exc is not value
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163 except RuntimeError as exc:
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164 # Don't re-raise the passed in exception
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165 if exc is value:
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166 return False
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167 # Likewise, avoid suppressing if a StopIteration exception
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168 # was passed to throw() and later wrapped into a RuntimeError
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169 # (see PEP 479).
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170 if _HAVE_EXCEPTION_CHAINING and exc.__cause__ is value:
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171 return False
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172 raise
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173 except:
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174 # only re-raise if it's *not* the exception that was
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175 # passed to throw(), because __exit__() must not raise
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176 # an exception unless __exit__() itself failed. But throw()
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177 # has to raise the exception to signal propagation, so this
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178 # fixes the impedance mismatch between the throw() protocol
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179 # and the __exit__() protocol.
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180 #
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181 if sys.exc_info()[1] is not value:
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182 raise
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183
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184
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185 def contextmanager(func):
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186 """@contextmanager decorator.
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187
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188 Typical usage:
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189
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190 @contextmanager
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191 def some_generator(<arguments>):
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192 <setup>
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193 try:
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194 yield <value>
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195 finally:
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196 <cleanup>
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197
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198 This makes this:
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199
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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200 with some_generator(<arguments>) as <variable>:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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201 <body>
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202
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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203 equivalent to this:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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204
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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205 <setup>
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206 try:
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207 <variable> = <value>
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208 <body>
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209 finally:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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210 <cleanup>
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211
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212 """
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213 @wraps(func)
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214 def helper(*args, **kwds):
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215 return _GeneratorContextManager(func, args, kwds)
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216 return helper
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217
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218
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219 class closing(object):
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220 """Context to automatically close something at the end of a block.
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221
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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222 Code like this:
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223
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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224 with closing(<module>.open(<arguments>)) as f:
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225 <block>
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226
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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227 is equivalent to this:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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228
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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229 f = <module>.open(<arguments>)
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230 try:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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231 <block>
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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232 finally:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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233 f.close()
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234
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
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235 """
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236 def __init__(self, thing):
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237 self.thing = thing
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238
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239 def __enter__(self):
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240 return self.thing
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241
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242 def __exit__(self, *exc_info):
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243 self.thing.close()
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244
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245
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246 class _RedirectStream(object):
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247
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248 _stream = None
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249
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250 def __init__(self, new_target):
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251 self._new_target = new_target
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252 # We use a list of old targets to make this CM re-entrant
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253 self._old_targets = []
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254
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255 def __enter__(self):
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256 self._old_targets.append(getattr(sys, self._stream))
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257 setattr(sys, self._stream, self._new_target)
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258 return self._new_target
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259
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260 def __exit__(self, exctype, excinst, exctb):
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261 setattr(sys, self._stream, self._old_targets.pop())
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262
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263
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264 class redirect_stdout(_RedirectStream):
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265 """Context manager for temporarily redirecting stdout to another file.
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266
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267 # How to send help() to stderr
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268 with redirect_stdout(sys.stderr):
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269 help(dir)
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270
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271 # How to write help() to a file
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272 with open('help.txt', 'w') as f:
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273 with redirect_stdout(f):
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274 help(pow)
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275 """
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276
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277 _stream = "stdout"
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278
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279
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280 class redirect_stderr(_RedirectStream):
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281 """Context manager for temporarily redirecting stderr to another file."""
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282
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283 _stream = "stderr"
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284
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285
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286 class suppress(object):
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287 """Context manager to suppress specified exceptions
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288
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289 After the exception is suppressed, execution proceeds with the next
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290 statement following the with statement.
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291
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292 with suppress(FileNotFoundError):
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293 os.remove(somefile)
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294 # Execution still resumes here if the file was already removed
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295 """
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296
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297 def __init__(self, *exceptions):
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298 self._exceptions = exceptions
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299
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300 def __enter__(self):
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301 pass
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302
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303 def __exit__(self, exctype, excinst, exctb):
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304 # Unlike isinstance and issubclass, CPython exception handling
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305 # currently only looks at the concrete type hierarchy (ignoring
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306 # the instance and subclass checking hooks). While Guido considers
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307 # that a bug rather than a feature, it's a fairly hard one to fix
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308 # due to various internal implementation details. suppress provides
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309 # the simpler issubclass based semantics, rather than trying to
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310 # exactly reproduce the limitations of the CPython interpreter.
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311 #
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312 # See http://bugs.python.org/issue12029 for more details
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313 return exctype is not None and issubclass(exctype, self._exceptions)
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314
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315
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316 # Context manipulation is Python 3 only
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317 _HAVE_EXCEPTION_CHAINING = sys.version_info[0] >= 3
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318 if _HAVE_EXCEPTION_CHAINING:
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319 def _make_context_fixer(frame_exc):
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320 def _fix_exception_context(new_exc, old_exc):
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321 # Context may not be correct, so find the end of the chain
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322 while 1:
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323 exc_context = new_exc.__context__
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324 if exc_context is old_exc:
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325 # Context is already set correctly (see issue 20317)
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326 return
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327 if exc_context is None or exc_context is frame_exc:
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328 break
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329 new_exc = exc_context
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330 # Change the end of the chain to point to the exception
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331 # we expect it to reference
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332 new_exc.__context__ = old_exc
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333 return _fix_exception_context
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334
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335 def _reraise_with_existing_context(exc_details):
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336 try:
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337 # bare "raise exc_details[1]" replaces our carefully
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338 # set-up context
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339 fixed_ctx = exc_details[1].__context__
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340 raise exc_details[1]
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341 except BaseException:
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342 exc_details[1].__context__ = fixed_ctx
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343 raise
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344 else:
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345 # No exception context in Python 2
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346 def _make_context_fixer(frame_exc):
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347 return lambda new_exc, old_exc: None
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348
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349 # Use 3 argument raise in Python 2,
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350 # but use exec to avoid SyntaxError in Python 3
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351 def _reraise_with_existing_context(exc_details):
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352 exc_type, exc_value, exc_tb = exc_details
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353 exec("raise exc_type, exc_value, exc_tb")
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354
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355 # Handle old-style classes if they exist
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356 try:
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357 from types import InstanceType
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358 except ImportError:
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359 # Python 3 doesn't have old-style classes
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360 _get_type = type
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361 else:
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362 # Need to handle old-style context managers on Python 2
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363 def _get_type(obj):
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364 obj_type = type(obj)
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365 if obj_type is InstanceType:
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366 return obj.__class__ # Old-style class
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367 return obj_type # New-style class
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368
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369
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370 # Inspired by discussions on http://bugs.python.org/issue13585
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371 class ExitStack(object):
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372 """Context manager for dynamic management of a stack of exit callbacks
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373
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374 For example:
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375
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376 with ExitStack() as stack:
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377 files = [stack.enter_context(open(fname)) for fname in filenames]
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378 # All opened files will automatically be closed at the end of
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379 # the with statement, even if attempts to open files later
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380 # in the list raise an exception
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381
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382 """
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383 def __init__(self):
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384 self._exit_callbacks = deque()
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385
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386 def pop_all(self):
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387 """Preserve the context stack by transferring it to a new instance"""
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388 new_stack = type(self)()
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parents:
diff changeset
389 new_stack._exit_callbacks = self._exit_callbacks
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
390 self._exit_callbacks = deque()
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
391 return new_stack
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
392
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
393 def _push_cm_exit(self, cm, cm_exit):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
394 """Helper to correctly register callbacks to __exit__ methods"""
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
395 def _exit_wrapper(*exc_details):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
396 return cm_exit(cm, *exc_details)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
397 _exit_wrapper.__self__ = cm
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
398 self.push(_exit_wrapper)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
399
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
400 def push(self, exit):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
401 """Registers a callback with the standard __exit__ method signature
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
402
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
403 Can suppress exceptions the same way __exit__ methods can.
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
404
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
405 Also accepts any object with an __exit__ method (registering a call
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
406 to the method instead of the object itself)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
407 """
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
408 # We use an unbound method rather than a bound method to follow
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
409 # the standard lookup behaviour for special methods
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
410 _cb_type = _get_type(exit)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
411 try:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
412 exit_method = _cb_type.__exit__
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
413 except AttributeError:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
414 # Not a context manager, so assume its a callable
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
415 self._exit_callbacks.append(exit)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
416 else:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
417 self._push_cm_exit(exit, exit_method)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
418 return exit # Allow use as a decorator
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
419
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
420 def callback(self, callback, *args, **kwds):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
421 """Registers an arbitrary callback and arguments.
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
422
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
423 Cannot suppress exceptions.
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
424 """
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
425 def _exit_wrapper(exc_type, exc, tb):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
426 callback(*args, **kwds)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
427 # We changed the signature, so using @wraps is not appropriate, but
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
428 # setting __wrapped__ may still help with introspection
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
429 _exit_wrapper.__wrapped__ = callback
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
430 self.push(_exit_wrapper)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
431 return callback # Allow use as a decorator
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
432
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
433 def enter_context(self, cm):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
434 """Enters the supplied context manager
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
435
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
436 If successful, also pushes its __exit__ method as a callback and
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
437 returns the result of the __enter__ method.
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
438 """
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
439 # We look up the special methods on the type to match the with statement
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
440 _cm_type = _get_type(cm)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
441 _exit = _cm_type.__exit__
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
442 result = _cm_type.__enter__(cm)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
443 self._push_cm_exit(cm, _exit)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
444 return result
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
445
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
446 def close(self):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
447 """Immediately unwind the context stack"""
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
448 self.__exit__(None, None, None)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
449
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
450 def __enter__(self):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
451 return self
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
452
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
453 def __exit__(self, *exc_details):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
454 received_exc = exc_details[0] is not None
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
455
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
456 # We manipulate the exception state so it behaves as though
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
457 # we were actually nesting multiple with statements
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
458 frame_exc = sys.exc_info()[1]
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
459 _fix_exception_context = _make_context_fixer(frame_exc)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
460
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
461 # Callbacks are invoked in LIFO order to match the behaviour of
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
462 # nested context managers
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
463 suppressed_exc = False
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
464 pending_raise = False
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
465 while self._exit_callbacks:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
466 cb = self._exit_callbacks.pop()
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
467 try:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
468 if cb(*exc_details):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
469 suppressed_exc = True
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
470 pending_raise = False
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
471 exc_details = (None, None, None)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
472 except:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
473 new_exc_details = sys.exc_info()
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
474 # simulate the stack of exceptions by setting the context
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
475 _fix_exception_context(new_exc_details[1], exc_details[1])
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
476 pending_raise = True
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
477 exc_details = new_exc_details
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
478 if pending_raise:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
479 _reraise_with_existing_context(exc_details)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
480 return received_exc and suppressed_exc
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
481
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
482
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
483 # Preserve backwards compatibility
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
484 class ContextStack(ExitStack):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
485 """Backwards compatibility alias for ExitStack"""
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
486
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
487 def __init__(self):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
488 warnings.warn("ContextStack has been renamed to ExitStack",
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
489 DeprecationWarning)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
490 super(ContextStack, self).__init__()
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
491
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
492 def register_exit(self, callback):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
493 return self.push(callback)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
494
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
495 def register(self, callback, *args, **kwds):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
496 return self.callback(callback, *args, **kwds)
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
497
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
498 def preserve(self):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
499 return self.pop_all()
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
500
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
501
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
502 class nullcontext(AbstractContextManager):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
503 """Context manager that does no additional processing.
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
504 Used as a stand-in for a normal context manager, when a particular
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
505 block of code is only sometimes used with a normal context manager:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
506 cm = optional_cm if condition else nullcontext()
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
507 with cm:
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
508 # Perform operation, using optional_cm if condition is True
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
509 """
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
510
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
511 def __init__(self, enter_result=None):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
512 self.enter_result = enter_result
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
513
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
514 def __enter__(self):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
515 return self.enter_result
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
516
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
517 def __exit__(self, *excinfo):
9e54283cc701 "planemo upload commit d12c32a45bcd441307e632fca6d9af7d60289d44"
guerler
parents:
diff changeset
518 pass