class twisted.python.failure.Failure(BaseException): (source)
Known subclasses: twisted.spread.pb.CopiedFailure, twisted.spread.pb.CopyableFailure
A basic abstraction for an error that has occurred.
This is necessary because Python's built-in error mechanisms are inconvenient for asynchronous communication.
The stack and frame attributes contain frames. Each frame is a tuple of (funcName, fileName, lineNumber, localsItems, globalsItems), where localsItems and globalsItems are the contents of locals().items()/globals().items() for that frame, or an empty tuple if those details were not captured.
| Instance Variable | value | The exception instance responsible for this failure. |
| Instance Variable | type | The exception's class. |
| Instance Variable | stack | list of frames, innermost last, excluding Failure.__init__. |
| Instance Variable | frames | list of frames, innermost first. |
| Class Variable | pickled | Undocumented |
| Method | __init__ | Initialize me with an explanation of the error. |
| Instance Variable | count | Undocumented |
| Instance Variable | captureVars | Undocumented |
| Instance Variable | tb | Undocumented |
| Instance Variable | parents | Undocumented |
| Instance Variable | __dict__ | Undocumented |
| Method | trap | Trap this failure if its type is in a predetermined list. |
| Method | check | Check if this failure's type is in a predetermined list. |
| Method | raiseException | raise the original exception, preserving traceback information if available. |
| Method | throwExceptionIntoGenerator | Throw the original exception into the given generator, preserving traceback information if available. |
| Method | __repr__ | Undocumented |
| Method | __str__ | Undocumented |
| Method | __getstate__ | Avoid pickling objects in the traceback. |
| Method | cleanFailure | Remove references to other objects, replacing them with strings. |
| Method | getTracebackObject | Get an object that represents this Failure's stack that can be passed to traceback.extract_tb. |
| Method | getErrorMessage | Get a string of the exception which caused this Failure. |
| Method | getBriefTraceback | Undocumented |
| Method | getTraceback | Undocumented |
| Method | printTraceback | Emulate Python's standard error reporting mechanism. |
| Method | printBriefTraceback | Print a traceback as densely as possible. |
| Method | printDetailedTraceback | Print a traceback with detailed locals and globals information. |
| Class Variable | _yieldOpcode | Undocumented |
| Method | _extrapolate | Extrapolate from one failure into another, copying its stack frames. |
| Class Method | _findFailure | Find the failure that represents the exception currently in context. |
Initialize me with an explanation of the error.
By default, this will use the current exception (sys.exc_info()). However, if you want to specify a particular kind of failure, you can pass an exception as an argument.
If no exc_value is passed, then an "original" Failure will be searched for. If the current exception handler that this Failure is being constructed in is handling an exception raised by raiseException, then this Failure will act like the original Failure.
For exc_tb only traceback instances or None are allowed. If None is supplied for exc_value, the value of exc_tb is ignored, otherwise if exc_tb is None, it will be found from execution context (ie, sys.exc_info).
| Parameters | exc_value | Undocumented |
| exc_type | Undocumented | |
| exc_tb | Undocumented | |
| captureVars | if set, capture locals and globals of stack frames. This is pretty slow, and makes no difference unless you are going to use printDetailedTraceback. |
Trap this failure if its type is in a predetermined list.
This allows you to trap a Failure in an error callback. It will be automatically re-raised if it is not a type that you expect.
The reason for having this particular API is because it's very useful in Deferred errback chains:
def _ebFoo(self, failure):
r = failure.trap(Spam, Eggs)
print('The Failure is due to either Spam or Eggs!')
if r == Spam:
print('Spam did it!')
elif r == Eggs:
print('Eggs did it!')
If the failure is not a Spam or an Eggs, then the Failure will be 'passed on' to the next errback. In Python 2 the Failure will be raised; in Python 3 the underlying exception will be re-raised.
| Parameters | errorTypes | Undocumented (type: Exception) |
raise the original exception, preserving traceback information if available.
Throw the original exception into the given generator, preserving traceback information if available.
| Returns | The next value yielded from the generator. | |
| Raises | StopIteration | If there are no more values in the generator. |
| anything else | Anything that the generator raises. | |
Find the failure that represents the exception currently in context.
Remove references to other objects, replacing them with strings.
On Python 3, this will also set the __traceback__ attribute of the exception instance to None.
Get an object that represents this Failure's stack that can be passed to traceback.extract_tb.
If the original traceback object is still present, return that. If this traceback object has been lost but we still have the information, return a fake traceback object (see _Traceback). If there is no traceback information at all, return None.
Get a string of the exception which caused this Failure.
| Returns | Undocumented (type: str) | |
Emulate Python's standard error reporting mechanism.
| Parameters | file | If specified, a file-like object to which to write the traceback. |
| elideFrameworkCode | A flag indicating whether to attempt to remove uninteresting frames from within Twisted itself from the output. | |
| detail | A string indicating how much information to include in the traceback. Must be one of 'brief', 'default', or 'verbose'. |
Print a traceback as densely as possible.
Print a traceback with detailed locals and globals information.