How to print an exception in Python 3

Question

Right now  I catch the exception in the except Exception  clause  and do print exception   The result provides no information since it always prints  lt class  Exception  gt   I knew this used to work in python 2  but how do I do it in python3

User · Answer

Although if you want a code that is compatible with both python2 and python3 you can use this   import logging try      1 0 except Exception as e      if hasattr e   message            logging warning  python2           logging error e message      else          logging warning  python3           logging error e

User · Answer

Here is the way I like that prints out all of the error stack   import logging  try      1   0 except Exception as  e        any one of the follows        print logging traceback format exc        logging error logging traceback format exc      The output looks as the follows   ERROR root Traceback  most recent call last     File   PATH-TO-YOUR filename py   line 4  in  lt module gt      1   0 ZeroDivisionError  division by zero   LOGGING FORMAT    LOGGING FORMAT      asctime s n  File    pathname s   line   lineno d n    levelname s    message s

User · Answer

I ve use this    except  socket timeout  KeyboardInterrupt  as e      logging debug  Exception       format str e   str    split      3        break   Let me know if it does not work for you

User · Answer

These are the changes since python 2       try          1   0     except Exception as e     as opposed to except Exception  e                                  that will just look for two classes  Exception and e           for the repr         print repr e             for just the message  or str e   since print calls str under the hood         print e            the arguments that the exception has been called with             the first one is usually the message   OSError is different  though          print e args    You can look into the standard library module traceback for fancier stuff

User · Answer

In Python3   Let s say you want to handle an IndexError and print the traceback  you can do the following    from traceback import print tb  empty list       try       x   empty list 100  except IndexError as index error       print tb index error   traceback      Note  You can use the format tb function instead of print tb to get the traceback as a string for logging purposes   Hope this helps

User · Answer

I m guessing that you need to assign the Exception to a variable  As shown in the Python 3 tutorial   def fails        x   1   0  try      fails   except Exception as ex      print ex    To give a brief explanation  as is a pseudo-assignment keyword used in certain compound statements to assign or alias the preceding statement to a variable   In this case  as assigns the caught exception to a variable allowing for information about the exception to stored and used later  instead of needing to be dealt with immediately   This is discussed in detail in the Python 3 Language Reference  The try Statement      The other compound statement using as is the with statement    contextmanager def opening filename       f   open filename      try          yield f     finally          f close    with opening filename  as f           read data from f      Here  with statements are used to wrap the execution of a block with methods defined by context managers  This functions like an extended try   except   finally statement in a neat generator package  and the as statement assigns the generator-produced result from the context manager to a variable for extended use   This is discussed in detail in the Python 3 Language Reference  The with Statement      Finally  as can be used when importing modules  to alias a module to a different  usually shorter  name   import foo bar baz as fbb   This is discussed in detail in the Python 3 Language Reference  The import Statement

User · Answer

Try try      print undefined var except Exception as e      print e   this will print the representation given by e   str        quot name  undefined var  is not defined quot   you can also use  print repr e    which will include the Exception class name    quot NameError  quot name  undefined var  is not defined quot    quot

[python] How to print an exception in Python 3?

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