logging - string formating problems

[MRAB]

Werner F. Bruhin wrote:
> I am fully aware that the problem is in my code, however as getMessage 
> in logging.__init__.py does not catch the exception it is pretty 
> difficult to find the problem without manually inspecting any 
> logging.something statements.
> 
> My hack of logging.py is really a hack and I know that this can not be 
> used a patch but I hope that someone with more know how then me knows 
> how to improve the situation.
> 
> BTW, using the below hack was enough for me to mind the bad code in my 
> stuff, but it shouldn't have been this difficult.
> 
> Traceback (most recent call last):
>   File "C:\Python25\lib\logging\__init__.py", line 750, in emit
>     msg = self.format(record)
>   File "C:\Python25\lib\logging\__init__.py", line 636, in format
>     return fmt.format(record)
>   File "C:\Python25\lib\logging\__init__.py", line 424, in format
>     record.message = record.getMessage()
>   File "C:\Python25\lib\logging\__init__.py", line 288, in getMessage
>     msg = msg % self.args
> TypeError: not all arguments converted during string formatting
> 
> 
> Then I hack logging.py and change line 288 in getMessage from:
>             msg = msg % self.args
> 
> to:
>             try:
>                 msg = msg % self.args
>             except:
>                 print 'msg: %s' % msg
>                 print 'args: %s' % self.args
>                 print traceback.format_exc()
> 
> I get the following which helps a lot more in finding were in my code I 
> have the problem:
> 
> msg: ping_min: 1
> args: replace
> Traceback (most recent call last):
>   File "C:\Python25\lib\logging\__init__.py", line 290, in getMessage
>     msg = msg % self.args
> TypeError: not all arguments converted during string formatting
> 
> 
> As mentioned above, I know the above code is not good enough at all, but 
> I hope that maybe Vinay Sajip or someone else with more know how then I 
> have can come up with a patch which will make this type of situation 
> easier.
> 
It looks like what you need is for the module to record the exception in
the log you're generating as a "logging error" or some such. BTW, you 
should catch only TypeError and not use an empty "except":

     try:
         msg = msg % self.args
     except TypeError:
         msg = 'Logging error: msg is %s, args is %s' % (repr(msg), 
repr(self.args))
         msg += traceback.format_exc()

(needs tidying up, of course!)