Create Error Message Python
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you have probably seen some. There are (at least) two distinguishable kinds of errors: syntax errors and exceptions. 8.1. Syntax Errors¶ Syntax errors, also known as parsing errors, are perhaps the most common print error message python kind of complaint you get while you are still learning Python: >>> while True get error message python print 'Hello world' File "
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in the example, the error is detected at the keyword print, since a colon (':') is missing before it. File name and line number are printed so you know where to look in case the input came from a script. 8.2. Exceptions¶ Even if a statement or expression is syntactically correct, it may cause an error when an attempt is made to execute it. Errors detected during execution python print error message except are called exceptions and are not unconditionally fatal: you will soon learn how to handle them in Python programs. Most exceptions are not handled by programs, however, and result in error messages as shown here: >>> 10 * (1/0) Traceback (most recent call last): File "
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Python Create Error Class
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Exception Message Python 3
Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, https://docs.python.org/2/tutorial/errors.html helping each other. Join them; it only takes a minute: Sign up Manually raising (throwing) an exception in Python up vote 783 down vote favorite 184 How can I raise an exception in Python so that it can later be caught via an except block? python exception exception-handling share|improve this question edited Feb 3 '15 at 14:37 http://stackoverflow.com/questions/2052390/manually-raising-throwing-an-exception-in-python DavidRR 5,13472747 asked Jan 12 '10 at 21:07 TIMEX 40.4k195519823 add a comment| 3 Answers 3 active oldest votes up vote 763 down vote accepted How do I manually throw/raise an exception in Python? Use the most specific Exception constructor that semantically fits your issue. Be specific in your message, e.g.: raise ValueError('A very specific bad thing happened') Don't do this: Avoid raising a generic Exception, to catch it, you'll have to catch all other more specific exceptions that subclass it. Hiding bugs raise Exception('I know Python!') # don't, if you catch, likely to hide bugs. For example: def demo_bad_catch(): try: raise ValueError('represents a hidden bug, do not catch this') raise Exception('This is the exception you expect to handle') except Exception as error: print('caught this error: ' + repr(error)) >>> demo_bad_catch() caught this error: ValueError('represents a hidden bug, do not catch this',) Won't catch and more specific catches won't catch the general exception: def demo_no_catch(): try: raise Exception('general exceptions not caught by specific handling') except ValueError as e:
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the http://stackoverflow.com/questions/9157210/how-do-i-raise-the-same-exception-with-a-custom-message-in-python workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. error message Join them; it only takes a minute: Sign up How do I raise the same Exception with a custom message in Python? up vote 43 down vote favorite 14 I have this try block in my code: try: do_something_that_might_raise_an_exception() except ValueError as err: errmsg = 'My custom error message.' raise ValueError(errmsg) Strictly speaking, I am actually raising another ValueError, error message python not the ValueError thrown by do_something...(), which is referred to as err in this case. How do I attach a custom message to err? I try the following code but fails due to err, a ValueError instance, not being callable: try: do_something_that_might_raise_an_exception() except ValueError as err: errmsg = 'My custom error message.' raise err(errmsg) python exception message share|improve this question asked Feb 6 '12 at 8:07 Kit 7,6311463117 Don't have an answer, but curious why? –Hamish Feb 6 '12 at 8:14 5 @Hamish, attaching additional information and re-raising exceptions can be very helpful when debugging. –Johan Lundberg Feb 6 '12 at 9:39 @Johan Absolutely - and that's what a stacktrace is for. Can't quite understand why you'd edit the existing error message instead of raising a new error. –Hamish Feb 6 '12 at 21:18 @Hamish. Sure but you can add other stuff. For your question, have a look at my answer and the example of UnicodeDecodeError. If you have comments on that perhaps comment my answer instead. –Johan