returning traceback strings

holger krekel pyth at devel.trillke.net
Fri Jun 14 00:38:53 CEST 2002


Matthew Boedicker wrote:
> Hello,
> 
> I am looking for something exactly like traceback.print_exc(), but instead
> of writing the traceback text to a filehandle, I want it to return it to
> me as a string.  I was unable to find any way to do this using the traceback
> module, since everything there seems to be in terms of file handles being
> passed around.
> 
> The problem is I need to pass the entire multi-line traceback string to a
> file-like object's write() method in one call, not line by line.
> 
> This is the best workaround I was able to come up with:
> 
> import cStringIO
> import traceback
> 
> def print_exc_str():
>     buf = cStringIO.StringIO()
>     traceback.print_exc(file=buf)
>     return buf.getvalue()

this is a straightforward solution. if you don't want
cStringIO you could do:

import traceback

class fakefile(list):
    write=list.append

def get_exception():
    ff=fakefile()
    traceback.print_exc(file=ff)
    return "\n".join(ff)
    
> Any suggestions for a better way?  What about the traceback module using
> strings internally, and wrapping another layer around that to write to files
> and file-like objects?

The traceback module seems to route every print through '_print' (look
into traceback.py) but you can't just replace 'file' with a string,
because strings are immutable. You have to use a mutable type
like a list <wink>. 

    holger





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