twisted.python.failure.Failure

class documentation

class 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.

Method	`__getstate__`	Avoid pickling objects in the traceback.
Method	`__init__`	Initialize me with an explanation of the error.
Method	`__repr__`	Undocumented
Method	`__str__`	Undocumented
Method	`check`	Check if this failure's type is in a predetermined list.
Method	`cleanFailure`	Remove references to other objects, replacing them with strings.
Method	`getBriefTraceback`	Undocumented
Method	`getErrorMessage`	Get a string of the exception which caused this Failure.
Method	`getTraceback`	Undocumented
Method	`getTracebackObject`	Get an object that represents this Failure's stack that can be passed to traceback.extract_tb.
Method	`printBriefTraceback`	Print a traceback as densely as possible.
Method	`printDetailedTraceback`	Print a traceback with detailed locals and globals information.
Method	`printTraceback`	Emulate Python's standard error reporting mechanism.
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	`trap`	Trap this failure if its type is in a predetermined list.
Class Variable	`pickled`	Undocumented
Instance Variable	`__dict__`	Undocumented
Instance Variable	`captureVars`	Undocumented
Instance Variable	`count`	Undocumented
Instance Variable	`frames`	list of frames, innermost first.
Instance Variable	`parents`	Undocumented
Instance Variable	`stack`	list of frames, innermost last, excluding `Failure.__init__`.
Instance Variable	`tb`	Undocumented
Instance Variable	`type`	The exception's class.
Instance Variable	`value`	The exception instance responsible for this failure.
Class Method	`_findFailure`	Find the failure that represents the exception currently in context.
Method	`_extrapolate`	Extrapolate from one failure into another, copying its stack frames.
Class Variable	`_yieldOpcode`	Undocumented

def __getstate__(self): (source)

Avoid pickling objects in the traceback.

def __init__(self, exc_value=None, exc_type=None, exc_tb=None, captureVars=False): (source)

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`.

def __repr__(self): (source)

Undocumented

Returns
`str`	Undocumented

def __str__(self): (source)

Undocumented

Returns
`str`	Undocumented

def check(self, *errorTypes): (source)

Check if this failure's type is in a predetermined list.

Parameters
*errorTypes:list of `Exception` classes or fully-qualified class names.	Undocumented
Returns
the matching `Exception` type, or None if no match.

def cleanFailure(self): (source)

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.

def getBriefTraceback(self): (source)

Undocumented

Returns
`str`	Undocumented

def getErrorMessage(self): (source)

Get a string of the exception which caused this Failure.

Returns
`str`	Undocumented

def getTraceback(self, elideFrameworkCode=0, detail='default'): (source)

Undocumented

Parameters
elideFrameworkCode:`int`	Undocumented
detail:`str`	Undocumented
Returns
`str`	Undocumented

def getTracebackObject(self): (source)

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.

def printBriefTraceback(self, file=None, elideFrameworkCode=0): (source)

Print a traceback as densely as possible.

def printDetailedTraceback(self, file=None, elideFrameworkCode=0): (source)

Print a traceback with detailed locals and globals information.

def printTraceback(self, file=None, elideFrameworkCode=False, detail='default'): (source)

overridden in twisted.spread.pb.CopiedFailure

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'`.

def raiseException(self): (source)

raise the original exception, preserving traceback information if available.

@_extraneous
def throwExceptionIntoGenerator(self, g): (source)

overridden in twisted.spread.pb.CopiedFailure

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.

def trap(self, *errorTypes): (source)

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:`Exception`	Undocumented

pickled: int = (source)

Undocumented

__dict__ = (source)

Undocumented

captureVars = (source)

Undocumented

count = (source)

Undocumented

frames = (source)

list of frames, innermost first.

parents = (source)

Undocumented

stack: list = (source)

list of frames, innermost last, excluding Failure.__init__.

tb = (source)

Undocumented

type = (source)

overridden in twisted.spread.pb.CopiedFailure

The exception's class.

value = (source)

overridden in twisted.spread.pb.CopiedFailure

The exception instance responsible for this failure.

@classmethod
def _findFailure(cls): (source)

Find the failure that represents the exception currently in context.

def _extrapolate(self, otherFailure): (source)

Extrapolate from one failure into another, copying its stack frames.

Parameters
otherFailure:`Failure`	Another `Failure`, whose traceback information, if any, should be preserved as part of the stack presented by this one.

_yieldOpcode = (source)

Undocumented