What about try:except:finally
Thomas Weholt
Does python support, or if not, would it be cool to have support for :
try:
# some code
except :
# catch exception
finally:
# clean up whatever
Thomas
Olivier Dagenais
anything else. I have a feeling you would need to do:
try:
#init
try:
# stuff
except:
# stuff
finally:
#stuff
...that is, assuming that your "except" would only catch specific exceptions
that you would want to prepare an error message with.
--
----------------------------------------------------------------------
Olivier A. Dagenais - Carleton University - Computer Science III
"Thomas Weholt" <tho...@cintra.no> wrote in message
news:3967d908....@news.online.no...
Peter Schneider-Kamp
>
> try:
> # some code
> except :
> # catch exception
> finally:
> # clean up whatever
You can always use
try:
try:
# some code
except:
# catch exception
finally:
# clean up whatever
Not quite as elegant, but do we really need
an extra syntax for that?
wanting-orthogonal-persistence-ly y'rs
Peter
--
Peter Schneider-Kamp ++47-7388-7331
Herman Krags veg 51-11 mailto:pe...@schneider-kamp.de
N-7050 Trondheim http://schneider-kamp.de
Richard Gruet
Thomas Weholt wrote:
> Hi,
>
> Does python support, or if not, would it be cool to have support for :
>
> try:
> # some code
> except :
> # catch exception
> finally:
> # clean up whatever
>
> Thomas
no, these are 2 separate constructs that you can embed:
try:
try:
# some code
except:
# catch exception
finally:
# clean-up whatever
Your proposition makes sense but it's little gain, and with separate
constructs you can do a lot of different things in the SAME try/finally,
e.g:
# Allocate resource (eg. open file)
try:
# do something
try:
# some code
except:
# catch exception
# do something else
try:
# some code
except:
# catch exception
finally:
# release resource (eg close file)
Cheers,
Richard
Jon McLin
try:
# some code
except:
# catch exception
finally:
Alan Daniels
[paraphrased...]
>Does python support, or if not, would it be cool to have support for
>try/except/finally?
No, but just use try/except/else instead. Why it's "else" instead of
"finally", I have no idea, but this works just fine. Example:
try:
x = 1
except NameError:
print "Ack!"
else:
print "Woohoo!"
--
============================================================
Alan Daniels
dan...@mindspring.com
Chris Withers
> >Does python support, or if not, would it be cool to have support for
> >try/except/finally?
>
> No, but just use try/except/else instead. Why it's "else" instead of
> "finally", I have no idea, but this works just fine. Example:
Actually, yes it does ;-)
...but it does something different. I read the discription on page 50 of
David Beazely's Python Essential Reference, but it didn't make much
sense to me :S
cheers,
Chris
Thomas Wouters
The 'else' is called 'else' because it's similar to the 'else' in 'if'
clauses and 'for' and 'while' loops: the 'else' clause of a 'try/except'
only gets executed when *no* exception occurs. 'finally', however, will
alway be called on the 'way out' of the try-block, wether something went
wrong or not.
--
Thomas Wouters <tho...@xs4all.net>
Hi! I'm a .signature virus! copy me into your .signature file to help me spread!
Matthew Schinckel
> On Fri, 07 Jul 2000 13:20:25 GMT, Thomas Weholt <tho...@cintra.no> wrote:
>
> [paraphrased...]
> >Does python support, or if not, would it be cool to have support for
> >try/except/finally?
>
> No, but just use try/except/else instead. Why it's "else" instead of
> "finally", I have no idea, but this works just fine. Example:
Yes, but if you want a statement executed regardless of whether there was
an exception or not, you need to use a finally clause.
--
Matthew Schinckel <ma...@null.net>
What this country needs is a good five cent microcomputer.
Martin von Loewis
> Yes, but if you want a statement executed regardless of whether there was
> an exception or not, you need to use a finally clause.
That also shows that having try:except:finally is perhaps not a good
idea. Given
try:
A
except:
B
finally:
C
is that the same as
try:
try:
A
finally:
C
except:
B
or as
try:
try:
A
except:
B
finally:
C
or is it something else? If so, what would it be? And why not one of
the others?
Regards,
Martin
Tim Peters
Sorry that I haven't followed this whole thread, but if no old-timer has
pointed it out before, Python *used* to allow try/except/finally all at the
same level. For exactly the reason Martin gave here, that was removed
before Python's first public release. From Misc/HISTORY:
New features in 0.9.6:
- stricter try stmt syntax: cannot mix except and finally clauses on 1
try
The ambiguity Martin pointed out here was real: it's not at all obvious
what mixing them means, and about half <wink> the users guessed wrong about
what the implementation actually did.
explicit-is-better-than-implicit-ly y'rs - tim
Tomek Lisowski
do grup dyskusyjnych
napisał:rkl95.48923$W35.1...@news20.bellglobal.com...
> If I remember the tutorial correctly, it doesn't support finally with
> anything else. I have a feeling you would need to do:
>
> try:
> #init
> try:
> # stuff
> except:
> # stuff
> finally:
> #stuff
>
> ...that is, assuming that your "except" would only catch specific
exceptions
> that you would want to prepare an error message with.
Please quote the original message next time.
At least I can see in your example one error. If you place try...except...
within try...finally..., the latter construct won't see any exceptions at
all. Moreover, if #init raises an exception, it won't be caught!
I see it more logical in this order:
try:
try:
#init
#stuff
except:
#stuff
finally:
#stuff
If you want separate behaviour for exceptions in #init and the first #stuff
sections, add yet another try...except... contruct. If #init is safe, and
will not raise any exceptions, it can be placed outside of the inner
try...except... construct.
Tomek Lisowski
Olivier Dagenais
exception, and that the inner "except" block would re-throw if it was really
bad:
try:
# safe init stuff
try:
# not so safe stuff
except:
# is it an exception we want to handle?
# if so, handle, send an error message, etc..
# otherwise, re-throw the error
finally:
# de-init stuff
--
----------------------------------------------------------------------
Olivier A. Dagenais - Carleton University - Computer Science III
"Tomek Lisowski" <Lisowsk...@sssa.nospam.pl> wrote in message
news:ICWa5.46250$Qw1.1...@news.tpnet.pl...
> U?ytkownik Olivier Dagenais w wiadomo?ci
> do grup dyskusyjnych
> napisa?:rkl95.48923$W35.1...@news20.bellglobal.com...