Re: raise errors

[Gabriel Genellina]

En Mon, 21 Sep 2009 06:17:20 -0300, daved170  escribió:


I need help with exceptions raising.
My goal is to print at the outer functions all the errors including
the most inner one.


The default exception report contains a lot of information, you don't have  
to do anything special.



def foo1(self):
   try:
foo2()
   except ? :
 print "outer Err at foo1" + ??

def foo2(self):
   try:
error occured
   except ? :
 raise "inner Err at foo2"


The bare bones structure is:

def foo1():
  foo2()

def foo2():
  undefinedname()

foo1()

and you get this error:

D:\temp>python test638580.py
Traceback (most recent call last):
  File "test638580.py", line 7, in 
foo1()
  File "test638580.py", line 2, in foo1
foo2()
  File "test638580.py", line 5, in foo2
undefinedname()
NameError: global name 'undefinedname' is not defined



I would like the print to be : outer Err at foo1 , inner Err at foo1


It already includes that info.

  File "test638580.py", line 2, in foo1
foo2()

means that in line 2 of test638580.py, inside function foo1, there was a  
call to foo2.


  File "test638580.py", line 5, in foo2
undefinedname()

and that means that foo2 tried to call undefinedname.

  NameError: global name 'undefinedname' is not defined

And that's the actual error.

Do you want it to be more nicely formatted? Do you want to include  
additional information? Or what?


--
Gabriel Genellina

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Re: raise errors

[Benjamin Kaplan]

On Mon, Sep 21, 2009 at 5:17 AM, daved170  wrote:
> Hi everybody,
> I need help with exceptions raising.
> My goal is to print at the outer functions all the errors including
> the most inner one.
>
> For example:
>
> def foo1(self):
>   try:
>        foo2()
>   except ? :
>         print "outer Err at foo1" + ??
>
> def foo2(self):
>   try:
>        error occured
>   except ? :
>         raise "inner Err at foo2"
>
>
> the ? remarks that I have no idea what to use.
>
> I would like the print to be : outer Err at foo1 , inner Err at foo1
>
> thanks
> daved
> --

First of all, what version of Python are you using? String exceptions
are deprecated in Python 2.5 and removed in 2.6. You should switch to
using Exceptions. In particular, you'll probably want to subclass
Exception.

String exceptions use the syntax "except 'exception string':" which
means you need to know the string ahead of time. You'll instead want
to do this.

def foo1() :
   try :
 foo2()
   except Exception, e :
  print "outer exception at foo1, %s" % str(e)

def foo2() :
   raise Exception("inner exception at foo2")

In Python 3.x, the syntax changed to "except Exception as e" but that
syntax isn't available in versions prior to 2.6


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Re: raise errors

[Peter Otten]

daved170 wrote:

> I need help with exceptions raising.
> My goal is to print at the outer functions all the errors including
> the most inner one.
> 
> For example:
> 
> def foo1(self):
>try:
> foo2()
>except ? :
>  print "outer Err at foo1" + ??
> 
> def foo2(self):
>try:
> error occured
>except ? :
>  raise "inner Err at foo2"
> 
> 
> the ? remarks that I have no idea what to use.
> 
> I would like the print to be : outer Err at foo1 , inner Err at foo1

Have a look at the traceback module. Example:

>>> def foo():
... try:
... oops
... except:
... traceback.print_exc()
... raise
...
>>> def bar():
... try:
... foo()
... except:
... traceback.print_exc()
...
>>> import traceback
>>> bar()
Traceback (most recent call last):
  File "", line 3, in foo
NameError: global name 'oops' is not defined
Traceback (most recent call last):
  File "", line 3, in bar
  File "", line 3, in foo
NameError: global name 'oops' is not defined

Peter

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Re: raise errors

[Ulrich Eckhardt]

daved170 wrote:
> I need help with exceptions raising.
> My goal is to print at the outer functions all the errors including
> the most inner one.
> 
> For example:
> 
> def foo1(self):
>try:
> foo2()
>except ? :
>  print "outer Err at foo1" + ??
> 
> def foo2(self):
>try:
> error occured
>except ? :
>  raise "inner Err at foo2"
> 
> 
> the ? remarks that I have no idea what to use.
> 
> I would like the print to be : outer Err at foo1 , inner Err at foo1

Take a look at the builtin debugger facility, i.e. 'import pdb'. There, you
have a traceback module which might already give you what you want.

One more advise though: Do not catch exceptions you don't handle! Make sure
they can pass through your code without hurting anything and then catch and
log them in a place where you actually can handle them. In particular,
don't wrap each and every tiny morsel of code into try/except handlers as
you would (have to) do if you were using return values.

Uli

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