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Python Base Error Class


But you may want to get rid of the deprecation error, of course. How do I install the latest OpenOffice? And in that case you can do the __init__ and __str__ needed there, so you don't have to repeat it for every exception. What's the difference between `su -` and `su --login`? http://caribtechsxm.com/python-exception/python-error-class.php

Thanks for adding it. I was tripped up by the following deprecation warning in Python 2.6.2: >>> class MyError(Exception): ... Critique of the top answer Maybe I missed the question, but why not: class MyException(Exception): pass Again, the problem with the above is that in order to catch it, you'll either asked 7 years ago viewed 235699 times active 1 month ago Blog Stack Overflow Podcast #92 - The Guerilla Guide to Interviewing Linked 1 How to write a custom exception class https://docs.python.org/2/library/exceptions.html

Python Exception Message

share|improve this answer edited Jun 13 '14 at 23:39 Jim Ferrans 17.7k74167 answered Apr 22 '12 at 18:18 frnknstn 2,3321912 4 It looks like you shouldn't inherit from base exception. That seems like a lot of typing, is it necessary? 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 This talk elaborates the topic: youtu.be/o9pEzgHorH0?t=9m56s (sorry for directing out of the declaration details). –dmitry_romanov Nov 27 '14 at 12:02 | show 1 more comment 6 Answers 6 active oldest votes

In any case, you only need the __init__ or __str__ if you do something different from what Exception itself does. And because if the deprecation, you then need both, or you get an error. Browse other questions tagged python exception or ask your own question. Python Exception Class Methods I'll demonstrate both errors: >>> ValidationError('foo', 'bar', 'baz').message Traceback (most recent call last): File "", line 1, in ValidationError('foo', 'bar', 'baz').message TypeError: __init__() takes exactly 3 arguments (4 given) >>>

Teaching a blind student MATLAB programming Jokes about Monica's haircut Cant find the game to this melody. Python Custom Exception That's an interesting constraint that future users may not appreciate. arguments as any other builtin Error super(MyAppValueError, self).__init__(message, foo, *args) There's really no need to write your own __str__ or __repr__. Antsy permutations If Six Is Easy, Is Ten So Hard?

If you do need more than a single piece of information, then you should consider fully subclassing Exception. Python Errno Ugh. See docs.python.org/tutorial/… for more information. –Jeff Bradberry Aug 23 '09 at 21:58 1 Understood, but in addition "args" is a special member name for the Exception type. –Nelson Aug 23 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.

  1. You would need to do something like this: try: raise MyException({"message":"My hovercraft is full of animals", "animal":"eels"}) except MyException as e: details = e.args[0] print(details["animal"]) It is still possible to pass
  2. 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,
  3. The default str() and repr() methods in Exception seem to do a good job of printing out any arguments passed into the MyException() constructor.
  4. Update: two answers have suggested overriding __init__, and __str__/__unicode__/__repr__.
  5. By "modern Python" I mean something that will run in Python 2.5 but be 'correct' for the Python 2.6 and Python 3.* way of doing things.
  6. Will change it tomorrow –Alvaro Feb 4 '15 at 1:54 1 good critique!
  7. That means that if your exception is a type of a more specific exception, subclass that exception instead of the generic Exception (and the result will be that you still derive

Python Custom Exception

The builtin ones are very nice, and your cooperative inheritance ensures that you use it. https://pymotw.com/2/exceptions/ Next number in sequence, understand the 1st mistake to avoid the 2nd more hot questions question feed lang-py about us tour help blog chat data legal privacy policy work here advertising Python Exception Message 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 Python Valueerror Example That's not a whole lot of extra code you need per class. ;) share|improve this answer answered Aug 23 '09 at 21:58 Lennart Regebro 75k17134202 add a comment| Your Answer

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? check my blog Not the answer you're looking for? Nested apply function at a list Counterintuitive polarizing filters Which lane to enter on this roundabout? (UK) Why didn't Dave Lister go home? All user-defined exceptions should also be derived from this class. Python Filenotfounderror

The code that handles this exception will, ofc, import it –Alvaro Feb 3 '15 at 19:56 @Alvaro I didn't say it was wrong, it just has the downside of Basically, __init__ is setting self.args = args. –Jeff Bradberry Aug 23 '09 at 22:20 1 Critique of top answer here: stackoverflow.com/a/26938914/541136 –Aaron Hall Nov 14 '14 at 22:23 2 But simply calling the message variable something else than message does the trick. this content And if you have many exceptions in your application it's usually a good idea to have a common custom base class for all of them, so that users of your modules

What is summer in Spanish? "Estío" vs "verano" Why do you use Bitcoin addresses instead of public keys? Python Attributeerror Object Has No Attribute 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 Hot Network Questions How much are taxes for a postdoc in the United States?

Similar criticism to the below, but additionally that's not the way to initialize via super, and you'll get a DeprecationWarning if you access the message attribute: Edit: to override something (or

share|improve this answer edited Aug 23 '09 at 22:10 Bastien Léonard 31.3k106181 answered Aug 23 '09 at 21:46 M. def __init__(self, message): ... It's just deprecated. Python 3 Exceptions Something about Nintendo and Game Over Screen Baking at a lower temperature than the recipe calls for Help me remember which is which: "humoro" and "humuro" How to flood the entire

class NastyError(ExceptionTemplate): pass and if you don't like that default tuple-like representation, just add __str__ method to the ExceptionTemplate class, like: # ... 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, How does a jet's throttle actually work? http://caribtechsxm.com/python-exception/python-class-error-handling.php except NelsonsExceptions: ...

From Python Exceptions: The base class for all built-in exceptions. But in your case, did you consider ModelNotLoadedError as a type of LookupError? –Aaron Hall Feb 3 '15 at 21:16 1 Thanks! 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 I'm also fuzzily aware that Exception has some magic parameter args, but I've never known how to use it.

current community chat Stack Overflow Meta Stack Overflow your communities Sign up or log in to customize your list. 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 I'm creating a BI framework and I happen to need a ModelNotLoadedError. up vote 595 down vote favorite 158 What's the proper way to declare custom exception classes in modern Python?

Avoid passing a dict as a positional argument, future users of your code will thank you. python exception share|improve this question edited Jun 5 '12 at 20:37 Eitan T 27.9k113978 asked Aug 23 '09 at 21:29 Nelson 6,43532027 2 *args (or *foo, or *whatever, all that self.errors = errors That way you could pass dict of error messages to the second param, and get to it later with e.errors It also requires exactly two arguments to be Utku ALTINKAYA 1,6821626 add a comment| up vote 4 down vote No, "message" is not forbidden.

Is this using Exception.args? Join them; it only takes a minute: Sign up Proper way to declare custom exceptions in modern Python? If you want more flexibiilty from the exception, you could pass a dictionary as the argument: raise MyException({"message":"My hovercraft is full of animals", "animal":"eels"}) However, to get at those details in Is it good style in modern Python?

You application will work fine with using message.