Mathematics tenure-track committees: Mathjobs question How to remove screws from old decking Can you chain Tempestuous magic and War Caster? The correct answer is Aaron Hall's one. –David Wallace Feb 16 '15 at 9:38 | show 1 more comment up vote 15 down vote For the common case where you need It's times like this I wish I could give more than one downvote per answer. –David Wallace Jan 21 '15 at 22:23 9 @DavidWallace it's terrible that this has so And if you're using threading and sys.exc_info you may even get the wrong traceback (especially if you're using exception handling for control flow - which I'd personally tend to avoid.) Python check over here
I gather from PEP-352 that attribute did have a special meaning in 2.5 they're trying to deprecate away, so I guess that name (and that one alone) is now forbidden? share|improve this answer edited Feb 27 '15 at 17:20 Zero Piraeus 17.6k125899 answered Jan 12 '10 at 21:08 Gabriel Hurley 24.6k94578 4 But now how do you catch this exception? However since "except Exeption as e:" will catch any exception, it is usually better to define a custom exception (docs.python.org/tutorial/errors.html#user-defined-exceptions) and raise that ( "raise IKnowPythonError" ), catching it with "except In many similar cases it's a condition that isn't associated with a particular value. https://docs.python.org/2.7/tutorial/errors.html
Rather, the meaning is "control flow should never get here". –Evgeni Sergeev Sep 17 '15 at 1:31 @Two-BitAlchemist Assertions can be turned off, yes, but then you shouldn't use To ANYBODY reading this answer, DO NOT DO THIS EVER! For future posterity: PEP 0352's sample code for BaseException shows exactly what's going on with args, __str()__, etc. –Nelson Aug 24 '09 at 14:19 45 Generaly I believe it would except Exception("I know python!") doesn't work. –Jason Axelson Sep 7 '11 at 5:01 40 @JasonAxelson catch this with "except Exception as e:". "except" cannot discriminate on the exception message, but
log that a specific type of error happened, and then reraise. From Python Exceptions: The base class for all built-in exceptions. Prove sets equality. Python Exception Class Methods Should two DFAs be complete before making an intersection of them?
Interviewee offered code samples from current employer -- should I accept? Python Print Exception It is ENTIRELY the wrong way to do it. But in your case, did you consider ModelNotLoadedError as a type of LookupError? –Aaron Hall Feb 3 '15 at 21:16 1 Thanks! When in except clause When inside an except clause, you might want to, e.g.
Utku ALTINKAYA 1,6821626 add a comment| up vote 4 down vote No, "message" is not forbidden. http://stackoverflow.com/questions/1319615/proper-way-to-declare-custom-exceptions-in-modern-python Can't get much more pythonic than this: raise Exception("I know python!") See the raise statement docs for python if you'd like more info. Python Custom Exception It's interesting to know that the arguments passed to the constructor can be retrieved in the args attribute (it's a tuple). –Bastien Léonard Aug 23 '09 at 22:01 1 Hmm, Python Raise Valueerror Nor am I sure it's the right way to do things going forward; a lot of the discussion I found online suggested they were trying to do away with args in
Because if the message changes, then I have to change the exception check everywhere. check my blog I was tripped up by the following deprecation warning in Python 2.6.2: >>> class MyError(Exception): ... Next number in sequence, understand the 1st mistake to avoid the 2nd Can a nuclear detonation on Moon destroy life on Earth? If you're not checking for the right exception and don't have a reviewer that's aware of the issue, it could get into production. Python Exception Stack Trace
Only valid in much older versions of Python (2.4 and lower), you may still see people raising strings: raise 'message' # really really wrong. It's less efficient and more error prone. Also, you can at least provide a docstring (and not be forced to use the pass keyword): class MyAppValueError(ValueError): '''Raise when my specific value is wrong''' Set attributes you create yourself this content Jokes about Monica's haircut Why does a full moon seem uniformly bright from earth, shouldn't it be dimmer at the "border"?
What exactly does it mean for a scalar function to be Lorentz invariant? Python Filenotfounderror Does the Many Worlds interpretation of quantum mechanics necessarily imply every world exist? Deprecated Methods: These can easily hide and even get into production code.
So if you have def myfunction(*args), you can call it like myfunction("foo") or myfunction("foo", "bar") and the arguments will be accessible in the body of the function as the tuple args. Antsy permutations How can a nine tailed fox catch its prey? You application will work fine with using message. Python Catch Multiple Exceptions Is this diffeomorphism on standard two sphere an isometry?
That's an interesting constraint that future users may not appreciate. Why don't cameras offer more than 3 colour channels? (Or do they?) Steepest descent/gradient descent as dynamical system What exactly does it mean for a scalar function to be Lorentz invariant? If you use the deprecated message attribute, assigning it yourself will avoid a DeprecationWarning: class MyAppValueError(ValueError): '''Raise when a specific subset of values in context of app is wrong''' def __init__(self, have a peek at these guys You want to raise an exception/error, and doing them will raise an error, but not the one intended!
Good parallels with the talk linked in the comment on the OP's question: stackoverflow.com/questions/1319615/… –Bodhi Apr 9 '15 at 0:16 "That's an interesting constraint that future users may not Ugh. asked 7 years ago viewed 235701 times active 1 month ago Blog Stack Overflow Podcast #92 - The Guerilla Guide to Interviewing Linked 1 How to write a custom exception class This is the syntax in Python 2: raise AppError, error, sys.exc_info() # avoid this. # Equivalently, as error *is* the second object: raise sys.exc_info(), sys.exc_info(), sys.exc_info() In Python 3: raise error.with_traceback(sys.exc_info())
I'll demonstrate both errors: >>> ValidationError('foo', 'bar', 'baz').message Traceback (most recent call last): File "
self.errors = errors That way you could pass dict of error messages to the second param, and get to it later with e.errors share|improve this answer edited Oct 11 '14 at The best way to do this while preserving the stack trace is to use a bare raise statement, e.g.: try: do_something_in_app_that_breaks_easily() except AppError as error: logger.error(error) raise # just this! # In all modern versions, this will actually raise a TypeError, because you're not raising a BaseException type. Why is AT&T's stock price declining, during the days that they announced the acquisition of Time Warner inc.?
except NelsonsExceptions: ... Browse other questions tagged python exception exception-handling or ask your own question. My primary goal is to follow whatever standard other exception classes have, so that (for instance) any extra string I include in the exception is printed out by whatever tool caught Not the answer you're looking for?
self.message = message ... >>> MyError("foo") _sandbox.py:3: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6 It seems crazy that BaseException has a special meaning for attributes named message. Or can I raise both, e.g. This works in Python 2 and 3. Set literal gives different result from set function call Can I send ethereum to a contract outside of its constructor?