Python Standard library-traceback module __python

Example 2-18 shows that the Traceback module allows you to print unusual trace return (traceback) information in your program, similar to what the interpreter did when the exception was not caught. As shown in Example 2-18. 2.11.0.1. Example 2-18. Print trace return information using the Traceback module file:traceback-example-1.py # note! Import

Example 2-18 shows that the Traceback module allows you to print unusual trace return (traceback) information in your program, similar to what the interpreter did when the exception was not caught. As shown in Example 2-18. 2.11.0.1. Example 2-18. Print trace return information using the Traceback module

file:traceback-example-1.py


# note! Importing the Traceback module messes up the

# exception state, so your better do ' here and '

# in the exception handler

Attention! The import Traceback clears the exception state, so

# It's better not to import the module in exception handling code

Import Traceback


Try

    Raise SyntaxError, "example"

Except

    Traceback.print_exc ()

Traceback (innermost last):

  File "traceback-example-1.py", line 7, in?

Syntaxerror:example

Example 2-19 uses the Stringio module to place trace return information in a string. 2.11.0.2. Example 2-19. Use the Traceback module to copy trace return information to a string

file:traceback-example-2.py


Import Traceback

Import Stringio


Try

    Raise IOError, "an I/O error occurred"

Except

    fp = Stringio.stringio ()

    Traceback.print_exc (FILE=FP)

    message = Fp.getvalue ()


    Print "failure! The error is: ", repr (message)

failure! The error was: ' Traceback (innermost last):/012  File

"Traceback-example-2.py", line 5, in?/012ioerror:an I/O error

occurred/012 '

You can use the EXTRACT_TB function to format trace return information and get a list of error messages, as shown in Example 2-20. 2.11.0.3. Example 2-20. Encoding traceback objects using Traceback module modules

 file:traceback-example-3.py 
 
 Import traceback 
 Import sys 
 
 def function (): 
 Raise IOError, "  An I/O error occurred "
 
 Try: 
 function () 
 except: 
 info = sys.exc_info () 
 for file, Lineno,  function, text in TRACEBACK.EXTRACT_TB (info[2]): 
 Print file, ' line ', Lineno, ' in ', function 
 Print ' => ', repr (text) 
 Print * * *%s:%s '% info[:2] 
 
  traceback-example-3.py line 8 in? 
 => ' Fun Ction () ' 
 traceback-example-3.py line 5 in function 
 => ' raise IOError, ' an I/O error occurred ' 
 * * exception S.ioerror:an I/O error occurred