Python Script Error Handling
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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 python catch all exceptions parsing errors, are perhaps the most common kind of complaint you get while
Python Exception Message
you are still learning Python: >>> while True print('Hello world') File "
Python Custom Exception
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 "
lots of Python script tools. Since other people were going to use these tools, I wanted my error handling to be robust and informative. python print exception This post is about some tips and tricks I discovered during this python try without except project. Error handling basics The basics of handling Python errors are covered in the 9.3 help topic Error
Python Try Except Else
handling with Python. The Python.org document Errors and Exceptions has more detailed information. Tip #1 - Use the arcgisscripting.ExecuteError exception In version 9.2, we introduced the arcgisscripting object along https://docs.python.org/3/tutorial/errors.html with a new exception class, arcgisscripting.ExecuteError. (This arcgisscripting.ExecuteError exception class wasn't documented in version 9.2, so few people knew about it.) The arcgisscripting.ExecuteError exception is thrown whenever a geoprocessing tool or geoprocessing function encounters an error. What this means is that you can divide errors into two groups, geoprocessing errors (those that throw the arcgisscripting.ExecuteError exception) and everything else. You https://blogs.esri.com/esri/arcgis/2008/12/01/tips-and-tricks-error-handling-in-python-script-tools/ can then handle the errors differently, as demonstrated in the code below: import arcgisscripting gp = arcgisscripting.create(9.3) try: result = gp.getcount("C:/blah.shp") # x = y # Return GEOPROCESSING specific errors # except arcgisscripting.ExecuteError: gp.AddError(gp.GetMessages(2)) # Return any PYTHON or system specific errors # except: gp.AddError("Python or system error occurred") The code above is used as the source for a script tool. To keep things simple, the script tool has no parameters. When the script tool is executed, the call to getcount produces an error because the dataset "C:/blah.shp" doesn't exist. As a result, the progress dialog looks as follows: To prove how geoprocessing errors and Python errors are handled differently, change the two lines of code as follows: # result = gp.getcount("C:/blah.shp") x = y Now when the script is executed, an error will occur because the variable ‘y' is undefined, and the progress dialog will display as follows: Tip #2 - Beware of getting error messages from a result object Before moving on, a quick word about the result object, shown below: result = gp.getcount("C:/blah.shp") If t
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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 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 up Python: about catching ANY exception up vote 240 down vote favorite 37 How can I write a try/except block that catches all exceptions? python share|improve this question edited Jul 10 '15 at 15:56 Mark Amery 24.2k12119151 asked Feb 14 '11 at 9:46 user469652 8,9372985137 1 Since I didn't see it linked here: docs.python.org/howto/doanddont.html#except. –delnan Feb 14 '11 at 16:32 3 Because I really don't know what exception to catch, and also the code is in a high level wrapper. –user469652 Feb 14 '11 at 20:45 1 In most cases you are, probably, doing smth wrong if you are trying to catch any exception. I mean you can simply misspell something in your code and you will even don't know about it. It is a good practice to catch specific exceptions. –vwvolodya Sep 4 '14 at 12:25 To be more precise, catching all possible exceptions is only a problem if they are caught silently. It's hard to think of where else this approach is appropriate, other than where the caught error messages are printed to sys.stderr and possibly logged. That is a perfectly valid and common exception. –Evgeni Sergeev May 7 at 4:28 add a comment| 6 Answers 6 active oldest votes up vote 185 down vote accepted You can but you shouldn't: try: do_something() except: print "Caught it!" However, this will also catch exceptions like KeyboardInterrupt and you usually don't want that, do you? Unless you re-raise the exception right away - see the following example from the docs: try: f = open('myfile.txt') s = f.readline() i = int(s.strip()) except IOError as (errno, strerror): print "I/O error({0}): {1}".format(errno, strerror) except ValueError: print "Could not convert data to an integer." except: print "Unexpected error:", sys.exc_info()[0] raise share|improve this answer edited Feb 3 '13 at 20:58 answered Feb 14 '11 at 9:49 Tim Pietzcker 197k27263354 11 Possible workaround: effbot.org/zone/stupid-exceptions-keyboardinterrupt.htm –Mikel Feb 14 '11 at 9:52 5 Your last statement is not true, you need to explicitly say except Exception: the bare