PyWart: Exception error paths far too verbose

Ramchandra Apte maniandram01 at gmail.com
Sun Jan 20 04:15:55 CET 2013


On Wednesday, 16 January 2013 15:23:55 UTC+5:30, Terry Reedy  wrote:
> On 1/16/2013 12:59 AM, Rick Johnson wrote:
> 
> >
> 
> > Python needs to trim the path to the source file from which the
> 
> > exception was caught and only display the relative path starting from
> 
> > your personal library folder.
> 
> >
> 
> > For example. Say your personal library exists in:
> 
> >
> 
> > C:\users\user\documents\python\lib
> 
> >
> 
> > ...then there is no need to post THAT portion of the path EVERY
> 
> > STINKING TIME! For instance, let's say a script at:
> 
> >
> 
> > C:\users\user\documents\python\lib\sound\effects\echo.py
> 
> >
> 
> > ...throws an error. What will we see?
> 
> >
> 
> > Traceback (most recent call last): File
> 
> > "C:\users\user\documents\python\lib\sound\effects\echo.py", line N,
> 
> > in BLAH
> 
> >
> 
> > Why do i need to see "C:\users\user\documents\python\lib" EVERY
> 
> > time?
> 
> >
> 
> > Since all directories *BELOW* the directory that holds your personal
> 
> > Python library are /superfluous/ when posting exceptions to stderr,
> 
> > trimming this bloat can really help to make exception messages easier
> 
> > to read.
> 
> >
> 
> > Traceback (most recent call last): File
> 
> > "...\sound\effects\reverb.py", line XXX, in YYY
> 
> 
> 
> I agree with the complaint and you may have the germ of a good idea. The 
> 
> problem is that for some tracebacks, paths jump all over the place 
> 
> rather than having a common prefix. Dealing with this might require 
> 
> preprocessing the entire traceback before iterating and printing each item.
> 
> 
> 
> Are you are aware of
> 
> '''
> 
> sys.excepthook(type, value, traceback)
> 
> 
> 
>      This function prints out a given traceback and exception to sys.stderr.
> 
> 
> 
>      When an exception is raised and uncaught, the interpreter calls 
> 
> sys.excepthook with three arguments, the exception class, exception 
> 
> instance, and a traceback object. In an interactive session this happens 
> 
> just before control is returned to the prompt; in a Python program this 
> 
> happens just before the program exits. The handling of such top-level 
> 
> exceptions can be customized by assigning another three-argument 
> 
> function to sys.excepthook.
> 
> '''
> 
> This is how some apps and environments customize exception reporting 
> 
> (and logging). I believe some people also put a replacement in their 
> 
> site module.
> 
> 
> 
>  >>> import sys; sys.excepthook
> 
> <built-in function excepthook>
> 
> 
> 
> I expect the default, excepthook, is something like
> 
> 
> 
> def excepthook(typ, value, traceback):
> 
>      print('Traceback (most recent call last):', file=sys.stderr)
> 
>      for item in traceback:
> 
>          print(format_tb_item(item), file=sys.stderr)
> 
>      print('{}: {}'.format(typ.__name__, value), file=sys.stderr)
> 
> 
> 
> (or the equivalent with sys.stderr.write)
> 
> 
> 
> What you want to change is format_tb_item (possibly, as I said, after 
> 
> scanning traceback before the print loop). If you come up with something 
> 
> nice, I would like to see it.
> 
> 
> 
> The only thing special that IDLE does now is to color the text red. I 
> 
> should sometime see how that is done. (Being able to doubleclick on an 
> 
> item and have IDLE open an edit window at the specified line would be 
> 
> really nice!)
> 
> 
> 
> -- 
> 
> Terry Jan Reedy

Right-click the file in the traceback and there is an "Go to file/line" option.



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