Coverage for wrapt/decorators.py: 0%

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 | """This module implements decorators for implementing other decorators as well as some commonly used decorators. """ import sys PY2 = sys.version_info[0] == 2 PY3 = sys.version_info[0] == 3 if PY3: string_types = str, import builtins exec_ = getattr(builtins, "exec") del builtins else: string_types = basestring, def exec_(_code_, _globs_=None, _locs_=None): """Execute code in a namespace.""" if _globs_ is None: frame = sys._getframe(1) _globs_ = frame.f_globals if _locs_ is None: _locs_ = frame.f_locals del frame elif _locs_ is None: _locs_ = _globs_ exec("""exec _code_ in _globs_, _locs_""") from functools import partial from inspect import ismethod, isclass, formatargspec from collections import namedtuple from threading import Lock, RLock try: from inspect import signature except ImportError: pass from .wrappers import (FunctionWrapper, BoundFunctionWrapper, ObjectProxy, CallableObjectProxy) # Adapter wrapper for the wrapped function which will overlay certain # properties from the adapter function onto the wrapped function so that # functions such as inspect.getargspec(), inspect.getfullargspec(), # inspect.signature() and inspect.getsource() return the correct results # one would expect. class _AdapterFunctionCode(CallableObjectProxy): def __init__(self, wrapped_code, adapter_code): super(_AdapterFunctionCode, self).__init__(wrapped_code) self._self_adapter_code = adapter_code @property def co_argcount(self): return self._self_adapter_code.co_argcount @property def co_code(self): return self._self_adapter_code.co_code @property def co_flags(self): return self._self_adapter_code.co_flags @property def co_kwonlyargcount(self): return self._self_adapter_code.co_kwonlyargcount @property def co_varnames(self): return self._self_adapter_code.co_varnames class _AdapterFunctionSurrogate(CallableObjectProxy): def __init__(self, wrapped, adapter): super(_AdapterFunctionSurrogate, self).__init__(wrapped) self._self_adapter = adapter @property def __code__(self): return _AdapterFunctionCode(self.__wrapped__.__code__, self._self_adapter.__code__) @property def __defaults__(self): return self._self_adapter.__defaults__ @property def __kwdefaults__(self): return self._self_adapter.__kwdefaults__ @property def __signature__(self): if 'signature' not in globals(): return self._self_adapter.__signature__ else: # Can't allow this to fail on Python 3 else it falls # through to using __wrapped__, but that will be the # wrong function we want to derive the signature # from. Thus generate the signature ourselves. return signature(self._self_adapter) if PY2: func_code = __code__ func_defaults = __defaults__ class _BoundAdapterWrapper(BoundFunctionWrapper): @property def __func__(self): return _AdapterFunctionSurrogate(self.__wrapped__.__func__, self._self_parent._self_adapter) if PY2: im_func = __func__ class AdapterWrapper(FunctionWrapper): __bound_function_wrapper__ = _BoundAdapterWrapper def __init__(self, *args, **kwargs): adapter = kwargs.pop('adapter') super(AdapterWrapper, self).__init__(*args, **kwargs) self._self_surrogate = _AdapterFunctionSurrogate( self.__wrapped__, adapter) self._self_adapter = adapter @property def __code__(self): return self._self_surrogate.__code__ @property def __defaults__(self): return self._self_surrogate.__defaults__ @property def __kwdefaults__(self): return self._self_surrogate.__kwdefaults__ if PY2: func_code = __code__ func_defaults = __defaults__ @property def __signature__(self): return self._self_surrogate.__signature__ class AdapterFactory(object): def __call__(self, wrapped): raise NotImplementedError() class DelegatedAdapterFactory(AdapterFactory): def __init__(self, factory): super(DelegatedAdapterFactory, self).__init__() self.factory = factory def __call__(self, wrapped): return self.factory(wrapped) adapter_factory = DelegatedAdapterFactory # Decorator for creating other decorators. This decorator and the # wrappers which they use are designed to properly preserve any name # attributes, function signatures etc, in addition to the wrappers # themselves acting like a transparent proxy for the original wrapped # function so the wrapper is effectively indistinguishable from the # original wrapped function. def decorator(wrapper=None, enabled=None, adapter=None): # The decorator should be supplied with a single positional argument # which is the wrapper function to be used to implement the # decorator. This may be preceded by a step whereby the keyword # arguments are supplied to customise the behaviour of the # decorator. The 'adapter' argument is used to optionally denote a # separate function which is notionally used by an adapter # decorator. In that case parts of the function '__code__' and # '__defaults__' attributes are used from the adapter function # rather than those of the wrapped function. This allows for the # argument specification from inspect.getargspec() and similar # functions to be overridden with a prototype for a different # function than what was wrapped. The 'enabled' argument provides a # way to enable/disable the use of the decorator. If the type of # 'enabled' is a boolean, then it is evaluated immediately and the # wrapper not even applied if it is False. If not a boolean, it will # be evaluated when the wrapper is called for an unbound wrapper, # and when binding occurs for a bound wrapper. When being evaluated, # if 'enabled' is callable it will be called to obtain the value to # be checked. If False, the wrapper will not be called and instead # the original wrapped function will be called directly instead. if wrapper is not None: # Helper function for creating wrapper of the appropriate # time when we need it down below. def _build(wrapped, wrapper, enabled=None, adapter=None): if adapter: if isinstance(adapter, AdapterFactory): adapter = adapter(wrapped) if not callable(adapter): ns = {} if not isinstance(adapter, string_types): adapter = formatargspec(*adapter) exec_('def adapter{0}: pass'.format(adapter), ns, ns) adapter = ns['adapter'] return AdapterWrapper(wrapped=wrapped, wrapper=wrapper, enabled=enabled, adapter=adapter) return FunctionWrapper(wrapped=wrapped, wrapper=wrapper, enabled=enabled) # The wrapper has been provided so return the final decorator. # The decorator is itself one of our function wrappers so we # can determine when it is applied to functions, instance methods # or class methods. This allows us to bind the instance or class # method so the appropriate self or cls attribute is supplied # when it is finally called. def _wrapper(wrapped, instance, args, kwargs): # We first check for the case where the decorator was applied # to a class type. # # @decorator # class mydecoratorclass(object): # def __init__(self, arg=None): # self.arg = arg # def __call__(self, wrapped, instance, args, kwargs): # return wrapped(*args, **kwargs) # # @mydecoratorclass(arg=1) # def function(): # pass # # In this case an instance of the class is to be used as the # decorator wrapper function. If args was empty at this point, # then it means that there were optional keyword arguments # supplied to be used when creating an instance of the class # to be used as the wrapper function. if instance is None and isclass(wrapped) and not args: # We still need to be passed the target function to be # wrapped as yet, so we need to return a further function # to be able to capture it. def _capture(target_wrapped): # Now have the target function to be wrapped and need # to create an instance of the class which is to act # as the decorator wrapper function. Before we do that, # we need to first check that use of the decorator # hadn't been disabled by a simple boolean. If it was, # the target function to be wrapped is returned instead. _enabled = enabled if type(_enabled) is bool: if not _enabled: return target_wrapped _enabled = None # Now create an instance of the class which is to act # as the decorator wrapper function. Any arguments had # to be supplied as keyword only arguments so that is # all we pass when creating it. target_wrapper = wrapped(**kwargs) # Finally build the wrapper itself and return it. return _build(target_wrapped, target_wrapper, _enabled, adapter) return _capture # We should always have the target function to be wrapped at # this point as the first (and only) value in args. target_wrapped = args[0] # Need to now check that use of the decorator hadn't been # disabled by a simple boolean. If it was, then target # function to be wrapped is returned instead. _enabled = enabled if type(_enabled) is bool: if not _enabled: return target_wrapped _enabled = None # We now need to build the wrapper, but there are a couple of # different cases we need to consider. if instance is None: if isclass(wrapped): # In this case the decorator was applied to a class # type but optional keyword arguments were not supplied # for initialising an instance of the class to be used # as the decorator wrapper function. # # @decorator # class mydecoratorclass(object): # def __init__(self, arg=None): # self.arg = arg # def __call__(self, wrapped, instance, # args, kwargs): # return wrapped(*args, **kwargs) # # @mydecoratorclass # def function(): # pass # # We still need to create an instance of the class to # be used as the decorator wrapper function, but no # arguments are pass. target_wrapper = wrapped() else: # In this case the decorator was applied to a normal # function, or possibly a static method of a class. # # @decorator # def mydecoratorfuntion(wrapped, instance, # args, kwargs): # return wrapped(*args, **kwargs) # # @mydecoratorfunction # def function(): # pass # # That normal function becomes the decorator wrapper # function. target_wrapper = wrapper else: if isclass(instance): # In this case the decorator was applied to a class # method. # # class myclass(object): # @decorator # @classmethod # def decoratorclassmethod(cls, wrapped, # instance, args, kwargs): # return wrapped(*args, **kwargs) # # instance = myclass() # # @instance.decoratorclassmethod # def function(): # pass # # This one is a bit strange because binding was actually # performed on the wrapper created by our decorator # factory. We need to apply that binding to the decorator # wrapper function which which the decorator factory # was applied to. target_wrapper = wrapper.__get__(None, instance) else: # In this case the decorator was applied to an instance # method. # # class myclass(object): # @decorator # def decoratorclassmethod(self, wrapped, # instance, args, kwargs): # return wrapped(*args, **kwargs) # # instance = myclass() # # @instance.decoratorclassmethod # def function(): # pass # # This one is a bit strange because binding was actually # performed on the wrapper created by our decorator # factory. We need to apply that binding to the decorator # wrapper function which which the decorator factory # was applied to. target_wrapper = wrapper.__get__(instance, type(instance)) # Finally build the wrapper itself and return it. return _build(target_wrapped, target_wrapper, _enabled, adapter) # We first return our magic function wrapper here so we can # determine in what context the decorator factory was used. In # other words, it is itself a universal decorator. return _build(wrapper, _wrapper) else: # The wrapper still has not been provided, so we are just # collecting the optional keyword arguments. Return the # decorator again wrapped in a partial using the collected # arguments. return partial(decorator, enabled=enabled, adapter=adapter) # Decorator for implementing thread synchronization. It can be used as a # decorator, in which case the synchronization context is determined by # what type of function is wrapped, or it can also be used as a context # manager, where the user needs to supply the correct synchronization # context. It is also possible to supply an object which appears to be a # synchronization primitive of some sort, by virtue of having release() # and acquire() methods. In that case that will be used directly as the # synchronization primitive without creating a separate lock against the # derived or supplied context. def synchronized(wrapped): # Determine if being passed an object which is a synchronization # primitive. We can't check by type for Lock, RLock, Semaphore etc, # as the means of creating them isn't the type. Therefore use the # existence of acquire() and release() methods. This is more # extensible anyway as it allows custom synchronization mechanisms. if hasattr(wrapped, 'acquire') and hasattr(wrapped, 'release'): # We remember what the original lock is and then return a new # decorator which accesses and locks it. When returning the new # decorator we wrap it with an object proxy so we can override # the context manager methods in case it is being used to wrap # synchronized statements with a 'with' statement. lock = wrapped @decorator def _synchronized(wrapped, instance, args, kwargs): # Execute the wrapped function while the original supplied # lock is held. with lock: return wrapped(*args, **kwargs) class _PartialDecorator(CallableObjectProxy): def __enter__(self): lock.acquire() return lock def __exit__(self, *args): lock.release() return _PartialDecorator(wrapped=_synchronized) # Following only apply when the lock is being created automatically # based on the context of what was supplied. In this case we supply # a final decorator, but need to use FunctionWrapper directly as we # want to derive from it to add context manager methods in case it is # being used to wrap synchronized statements with a 'with' statement. def _synchronized_lock(context): # Attempt to retrieve the lock for the specific context. lock = vars(context).get('_synchronized_lock', None) if lock is None: # There is no existing lock defined for the context we # are dealing with so we need to create one. This needs # to be done in a way to guarantee there is only one # created, even if multiple threads try and create it at # the same time. We can't always use the setdefault() # method on the __dict__ for the context. This is the # case where the context is a class, as __dict__ is # actually a dictproxy. What we therefore do is use a # meta lock on this wrapper itself, to control the # creation and assignment of the lock attribute against # the context. meta_lock = vars(synchronized).setdefault( '_synchronized_meta_lock', Lock()) with meta_lock: # We need to check again for whether the lock we want # exists in case two threads were trying to create it # at the same time and were competing to create the # meta lock. lock = vars(context).get('_synchronized_lock', None) if lock is None: lock = RLock() setattr(context, '_synchronized_lock', lock) return lock def _synchronized_wrapper(wrapped, instance, args, kwargs): # Execute the wrapped function while the lock for the # desired context is held. If instance is None then the # wrapped function is used as the context. with _synchronized_lock(instance or wrapped): return wrapped(*args, **kwargs) class _FinalDecorator(FunctionWrapper): def __enter__(self): self._self_lock = _synchronized_lock(self.__wrapped__) self._self_lock.acquire() return self._self_lock def __exit__(self, *args): self._self_lock.release() return _FinalDecorator(wrapped=wrapped, wrapper=_synchronized_wrapper)