[BangPypers] suppressing the exception stack trace
steve at lonetwin.net
Wed Sep 16 09:01:34 CEST 2009
On 09/16/2009 11:39 AM, Vishal wrote:
> On Tue, Sep 15, 2009 at 9:07 PM, steve <steve at lonetwin.net
> <mailto:steve at lonetwin.net>> wrote:
> On 09/15/2009 08:56 PM, Vishal wrote:
> I would like to raise an exception of type Exception(), however the
> regular exception stack trace needs to be supressed.
> This is needed in a function that takes raw_input() from the
> user and
> based on 'Y' or 'N', the function suspends further execution and
> to the python prompt or Hicontinues. An exit() brings it out of
> the python
> process....where as what is needed is coming back to the python
> I want a custom message to appear instead of a regular exception
> trace message.
> How to do this? any pointers...?
> Python 2.6 (r26:66714, Jun 8 2009, 16:07:29)
> [GCC 4.4.0 20090506 (Red Hat 4.4.0-4)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> > >> import traceback
> > >> try:
> ... 1 + "foo"
> ... except Exception, e:
> ... traceback.format_stack(limit=1)
> [' File "<stdin>", line 4, in <module>\n']
> > >> help(traceback)
> - steve
> Forgot to mention that we are currently stuck with python2.5.2
> As part of a debug/test hook, I would like to suspend further action of
> a program, after a certain point in the procedure. What I had come up
> with is a function named testHook() which does this:
> def testHook():
> choice = raw_input("Would you like to continue (Y or N): ")
> if(str(choice).lower() != 'y'):
> print("You chose not to go ahead. Ok!!\nAborting Now...")
> raise Exception("User initiated Abort...")
> except Exception:
> raise # re-raise it..so we come out of execution loop
> In this case, a stack trace gets printed out, before the string 'user
> initiated abort' comes up. I want to remove that stack trace...so it
> looks more clean to a user.
> What can be done in this case?
Well, I don't understand how and from what context you are calling testHook().
My first instinct is to ask, why you can't simply return instead of 'raise' on
an abort ? like so ...
choice = raw_input("Would you like to continue (Y or N): ")
if(str(choice).lower() != 'y'):
print("You chose not to go ahead. Ok!!\nAborting Now...")
print "User initiated Abort..."
return -1 # ...or any other value that makes sense to your app.
raise exc # re-raise the passed exception
In which case, I am assuming testHook() called like this:
1 + "foo"
except Exception, e:
> or any other way of creating such a hook?
Yes. The way I would do this sort of this is by using decorators:
>>> def testHook(func):
... def wrap_exception(*args):
... except Exception, e:
... choice = raw_input("Would you like to continue (Y or N): ")
... if (str(choice).lower() != 'y'):
... print("You chose not to go ahead. Ok!!\nAborting
... print "User initiated abort ..."
... print "on recieving %s" % e.message
... print "redirect to debugger in this block ..."
... return wrap_exception
... def main(a, b):
... return a + b
>>> main(1, "foo")
Would you like to continue (Y or N): n
You chose not to go ahead. Ok!!
User initiated abort ...
on recieving unsupported operand type(s) for +: 'int' and 'str'
Here is a good article for introducing decorators:
random non tech spiel: http://lonetwin.blogspot.com/
tech randomness: http://lonehacks.blogspot.com/
what i'm stumbling into: http://lonetwin.stumbleupon.com/
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