Python Throw Error Example
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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 python error types as parsing errors, are perhaps the most common kind of complaint you get
Python Raise Custom Exception
while you are still learning Python: >>> while True print 'Hello world' File "
Syntax For Raise Clause In Python
or expression is syntactically correct, it may cause an error when an attempt is made to execute it. Errors detected during execution 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 "
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings python exception message and policies of this site About Us Learn more about Stack Overflow is nested try block possible in python the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation
Python Print Exception
Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; https://docs.python.org/2.7/tutorial/errors.html it only takes a minute: Sign up Manually raising (throwing) an exception in Python up vote 800 down vote favorite 189 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 DavidRR 5,20472747 asked Jan 12 '10 at 21:07 http://stackoverflow.com/questions/2052390/manually-raising-throwing-an-exception-in-python TIMEX 41.2k201525826 add a comment| 3 Answers 3 active oldest votes up vote 787 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: print('we will not catch e') >>> demo_no_catch() Traceback (most recent call last): File " here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of http://stackoverflow.com/questions/13957829/how-to-use-raise-keyword-in-python 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 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign in python up How to use “raise” keyword in Python up vote 92 down vote favorite 10 So I have read the official definition of "raise", but I still don't quite understand what it is doing. In simplest terms, what is "raise"? A small example of it's use would help too. python keyword raise share|improve this question edited Sep 9 '13 at 15:44 Nakilon 19.7k86288 clause in python asked Dec 19 '12 at 17:27 Capurnicus 1,1883810 12 It's known as throw in some other languages. –voithos Dec 19 '12 at 17:29 add a comment| 5 Answers 5 active oldest votes up vote 120 down vote accepted It has 2 purposes. yentup has given the first one. It's used for raising your own errors. if something: raise Exception('My error!') The second is to reraise the current exception in an exception handler, so that it can be handled further up the call stack. try: generate_exception() except SomeException, e: if not can_handle(e): raise handle_exception(e) share|improve this answer edited Jan 9 '15 at 9:06 Phalgun 5971618 answered Dec 19 '12 at 17:32 Ignacio Vazquez-Abrams 447k64800956 12 I typed that in and got "global name 'error' is not defined". To others new to Python, you need "raise Exception('My error!')". You replace "error" with your Exception name. A list of standard exceptions you can use is here: docs.python.org/2/library/exceptions.html –Curtis Yallop Feb 28 '14 at 16:59 add a comment| Did you find this question interesting? Try our newsletter Sign up for our newsletter and get our top new questions del