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Python Return Error String


Browse other questions tagged python exception or ask your own question. After all, for could certainly have been written to not rely on exceptions to mark the end of a sequence. print("division by zero!") ... After having printed the text of the print statement, the execution does another loop. this contact form

I warned you.) Note This function is normally only used by code that needs to save and restore the error indicator temporarily; use PyErr_Fetch() to save the current exception state. Objects which, like files, provide predefined clean-up actions will indicate this in their documentation. Look at the following example, which asks the user for input until a valid integer has been entered, but allows the user to interrupt the program (using Control-C or whatever If the error is not handled or carefully propagated, additional calls into the Python/C API may not behave as intended and may fail in mysterious ways. http://stackoverflow.com/questions/16451514/returning-error-string-from-a-function-in-python

Python Get Exception Message

In-house Training Courses If you like it, we will come to your company or institute and provide a special training for your employees, as we've done it many times in Amsterdam So I guess the best is to do deal with e.args and str(e) depending on your needs (and possibly e.message if the lib you are using is relying on that mechanism). For more information about using the result object, see Getting results from a geoprocessing tool. If that attempt raises an exception, print our error string.

  1. So with a 90% chance of an exception being thrown in the code above, here are the numbers: using if statement: minimum: 1.35720682144 per_lookup: 1.35720682144e-06 using exception: minimum: 3.25777006149 per_lookup: 3.25777006149e-06
  2. Then if its type matches the exception named after the except keyword, the except clause is executed, and then execution continues after the try statement.
  3. print("executing finally clause") ... >>> divide(2, 1) result is 2.0 executing finally clause >>> divide(2, 0) division by zero!

If we simply raised a new exception from our except clause, the traceback point to our except clause and mask the real issue (not to mention confusing the user). Can a nuclear detonation on Moon destroy life on Earth? For completeness, here are all the variables: C Name Python Name Notes PyExc_BaseException BaseException (1), (4) PyExc_Exception Exception (1) PyExc_StandardError StandardError (1) PyExc_ArithmeticError

Handling run-time error: integer division or modulo by zero 8.4. Counterintuitive polarizing filters How do I install the latest OpenOffice? The return value has the same format as for extract_tb(). This means you cannot retrieve error messages from the Result object. import arcpy try: result = arcpy.GetCount_management("c:/data/rivers.shp") #

void PyErr_Clear()¶ Clear the error indicator. Python Custom Exception current community chat Stack Overflow Meta Stack Overflow your communities Sign up or log in to customize your list. PyObject* PyErr_SetFromWindowsErr(intierr)¶ Return value: Always NULL.This is a convenience function to raise WindowsError. PyObject* PyUnicodeDecodeError_GetReason(PyObject*exc)¶ PyObject* PyUnicodeEncodeError_GetReason(PyObject*exc)¶ PyObject* PyUnicodeTranslateError_GetReason(PyObject*exc)¶ Return the reason attribute of the given exception object.

Python Exception Class

The code prints the best run of executing each code block (LOOP_IF and LOOP_EXCEPT) 10,000,000 times. Test a variable in a set entries tag How to remove screws from old decking Can the notion of "squaring" be extended to other shapes? Python Get Exception Message The value -1 disables the feature; this is the initial state. Python Exception Stack Trace If you need to determine whether an exception was raised but don't intend to handle it, a simpler form of the raise statement allows you to re-raise the exception: >>>

Please donate. weblink So make sure that you call it properly: Let's assume that you saved this program as "exception_test.py". python python-2.7 python-3.x share|improve this question asked May 8 '13 at 22:48 KT100 4261925 2 Why not exceptions? –Waleed Khan May 8 '13 at 22:50 add a comment| 2 Answers Return 0 on success, -1 on failure. Syntax For Generic Except Clause In Python

This is because the Result object could not be created due to the tool's failure. This is true for all built-in exceptions, but need not be true for user-defined exceptions (although it is a useful convention). This is useful when you want to print stack traces under program control, such as in a "wrapper" around the interpreter. navigate here Sawyer) This website is supported by: Linux and Python Training Courses This topic in German / Deutsche Übersetzung: AusnahmebehandlungPython 3This is a tutorial in Python3, but this chapter of our course

Navigation index modules | next | previous | Python » 2.7.12 Documentation » The Python Standard Library » 28. Python Try Without Except The dict argument can be used to specify a dictionary of class variables and methods. In the first example above, if you were using a catch-all exception clause and a user presses Ctrl-C, generating a KeyboardInterrupt, you don't want the program to print "divide by zero".

If no exception occurs, the except clause is skipped and execution of the try statement is finished.

The Python Software Foundation is a non-profit corporation. You do not own a reference to the return value, so you do not need to Py_DECREF() it. Found a bug? Python Try Except Else If it's a matter of cleanup that should be run regardless of success or failure, then you would do: 1 try: 2 do_some_stuff() 3 finally: 4 cleanup_stuff() Finding Specific Exception Names

For instance, with pygraphviz, e.message is the only way to display correctly the exception, using str(e) will surround the message with u''. We want to keep some statistics on how often the function is misused and throws an exception, but we have no intention of actually handling the exception. Then if its type matches the exception named after the except keyword, the except clause is executed, and then execution continues after the try statement. his comment is here A raise statement can be used for this purpose.

If no exception occurs, the except clause is skipped and execution of the try statement is finished. Errors and Exceptions¶ Until now error messages haven't been more than mentioned, but if you have tried out the examples you have probably seen some. Note that the except block is only executed if Buffer returns an error.import arcpy import sys try: # Execute the Buffer tool # The try statement works as follows.

Did you have something in particular in mind? User-defined Exceptions¶ Programs may name their own exceptions by creating a new exception class (see Classes for more about Python classes). Exceptions should typically be derived from the Exception class, either directly or indirectly. The name "exception" in computer science has this meaning as well: It implies that the problem (the exception) doesn't occur frequently, i.e.

It isn't such a problem with python code, because the language is supposed to take care of fixing accounting-type invariants for you. -jJ) This is a better argument for *careful* use Lastly, let me argue against one of Joel's comments: "A better alternative is to have your functions return error values when things go wrong, and to deal with these explicitly, no Are illegal immigrants more likely to commit crimes? print 'Handling run-time error:', detail ...