Exception and finally question

[Erik Max Francis]

Tung Wai Yip wrote:

> How to I access the exception object in a handler?
>
> try:
>     raise NameError, 'HiThere'
> except NameError:
>     #how to print the message 'Hi There' here?

	try:
	    raise NameError, "Hi, there."
	except NameError, e:
	    print e

Note that e is actually the exception _object_, not just the string (or
whatever other argument) it was constructed with:

>>> try:
...  raise NameError, "What's up, dog?"
... except NameError, e:
...  print repr(e)
...  print str(e)
... 
<exceptions.NameError instance at 0x815b3b4>
What's up, dog?

> Why except and finally can't be used together? I like to log a error
> message if an exception is throw. And I a file to be guaranteed to be
> close. What can't I do them together?

By design.  Originally, as I understand it, Python supported a unified
try: ... except: ... finally: ... construct, but evidently it caused a
lot of confusion with newbies (personally, I don't see where the
confusion would be, but I guess that's because I'm familiar with the
construct from Java).  So in modern Python the try can either have an
except (perhaps several) or a finally, but not both.

You can get the effect you're probably looking for by just wrapping a
try: ... except: ... inside a try: ... finally: ...

	try:
	    try:
	        somethingThatMayRaise
	    except ...:
	        handleErrorCaseOrMaybeReraise
	finally:
	    doThisRegardless	

-- 
 Erik Max Francis / max at alcyone.com / http://www.alcyone.com/max/
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