Elements of an exception in Python - try, except, else, finally

Archive - Originally posted on "The Horse's Mouth" - 2015-02-28 14:45:53 - Graham Ellis
All the elements of an exception handler in one example ... [here]

try - enters at the top and continues through the block
except - jump to there is an exception is thrown
else - run after the try block completes without exception thrown
finally - always run after the other blocks have completed

A correctly running block
try - else - finally
(and code loops completes)

  -bash-4.1$ python duff

  (bfor) Exception demonstration

  

  (try-) Please enter a Python value: 44

  (else) Input accepted

  (finl) Tidying up

  

  (done) Value received: 44

  -bash-4.1$

A block with an error
try - except - finally
(and code loops back to have another go)

  -bash-4.1$ python duff

  (bfor) Exception demonstration

  

  (try-) Please enter a Python value: forty

  (exce) Not acceptable!

  (exce) Message:      name 'forty' is not defined

  (exce) Failure Type: NameError

  (finl) Tidying up

  

  (try-) Please enter a Python value:

Code

  while True:

            try:

                      n = input("(try-) Please enter a Python value: ")

            except KeyboardInterrupt:

                      print "(ex/k) You give up?"

                      print "(ex/k) Won't break me that way"

            except Exception,e:

                      print "(exce) Not acceptable!"

                      print "(exce) Message:     ",e

                      print "(exce) Failure Type:",e.__class__.__name__

            else:

                      print "(else) Input accepted"

                      break

            finally:

                      print "(finl) Tidying up\n"

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Elements of an exception in Python - try, except, else, finally