Re: Problem overriding sys.excepthook
Lunchtimemama wrote: What is the superior method of exception handling: ... For a start, note that the exception hook does not _really_ have to be in the main module, just imported before any protected code is to be executed. Having said that, what I personally typically do for exception trapping doesn't even require an exception hook. I will execute all my code from inside a try/except block in the main module. If the exception is invoked, you can query and get all the data about the exception like you are currently doing, and then re-raise the exception (or not). I haven't given too much thought to when I would set an exception hook. It seems like more of a debugger kind of thing. Especially if you have control over the entire app, a try/except at the top level feels cleaner to me. Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
Re: Problem overriding sys.excepthook
Try/except sounds like the way to go. Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Problem overriding sys.excepthook
Yo all, I'm getting into Python for the first time and I'm really
having a blast. I've hit a bit of a snag and was wondering if someone
could lend some insight. Here be the code:
import sys
def myexcepthook(type, value, tb):
import traceback
rawreport = traceback.format_exception(type, value, tb)
report = '\n'.join(rawreport)
errorlog = open('error.log','a')
errorlog.write(('%s\n' + '-'*30 + '\n\n') % report)
errorlog.close()
sys.excepthook = myexcepthook
Now here's the trouble: if I enter that line-by-line into the
interpreter in interactive mode, the custom exception hook will handle
all exceptions, but if I put that in a script that I run from the
shell, it only catches some exceptions. For example, it would catch an
undefined name, like if I just put:
spam
into the program above, the override would work. But if I made a
syntactical error, like:
1 = spam
then it would fall to the standard sys.excepthook. Is there some lazy
evaluation that I don't know about? I'm on Windows, if that makes a
difference. Thank for the help.
-LTM
--
http://mail.python.org/mailman/listinfo/python-list
Re: Problem overriding sys.excepthook
Lunchtimemama wrote:
Yo all, I'm getting into Python for the first time and I'm really
having a blast. I've hit a bit of a snag and was wondering if someone
could lend some insight. Here be the code:
import sys
def myexcepthook(type, value, tb):
import traceback
rawreport = traceback.format_exception(type, value, tb)
report = '\n'.join(rawreport)
errorlog = open('error.log','a')
errorlog.write(('%s\n' + '-'*30 + '\n\n') % report)
errorlog.close()
sys.excepthook = myexcepthook
Now here's the trouble: if I enter that line-by-line into the
interpreter in interactive mode, the custom exception hook will handle
all exceptions, but if I put that in a script that I run from the
shell, it only catches some exceptions. For example, it would catch an
undefined name, like if I just put:
spam
into the program above, the override would work. But if I made a
syntactical error, like:
1 = spam
then it would fall to the standard sys.excepthook. Is there some lazy
evaluation that I don't know about? I'm on Windows, if that makes a
difference. Thank for the help.
Python first compiles, then executes. However, since an import is
considered to be an execution, you can retrieve this sort of
compile-time error, but only on modules which are imported _after_ you
hook the exception handler.
HTH,
Pat
--
http://mail.python.org/mailman/listinfo/python-list
Re: Problem overriding sys.excepthook
Forgive my ignorance, but I'm not quite sure what you mean. I tried importing the traceback module at the beginning of the script, but that didn't make a difference. Could you provide example code to illustrate your comment? Thanks. -LTM -- http://mail.python.org/mailman/listinfo/python-list
Re: Problem overriding sys.excepthook
Lunchtimemama wrote: Forgive my ignorance, but I'm not quite sure what you mean. I tried importing the traceback module at the beginning of the script, but that didn't make a difference. Could you provide example code to illustrate your comment? Thanks. Assume your main module has your exception hook code in it, up to and including the line sys.excepthook = myexcepthook. As you have noticed, 1 = spam in your main module would cause an uncaught exception. This is because this exception is raised during the compilation phase of the module, before you hooked the exception vector. This is true NO MATTER WHERE in the main module this statement is -- Python will compile the entire module before executing it. Now assume that the statement 1 = spam is in module foo.py instead of in your main module. If you import foo at the top of your main module, you will have the same result but for slightly different reasons-- foo.py will be compiled during execution of the main module's import statement (although AFTER compilation of the main module), so the exception will still be raised before you have assigned your exception hook. HOWEVER, if you import foo AFTER the line sys.excepthook = myexcepthook, then the compilation of foo.py will occur after your exception hook has been set, and your exception handler will execute on the syntax error 1 = spam inside foo.py. So the bottom line is that you can't log syntax errors for your main module, but you _can_ log syntax errors for other modules which your main module imports. I think one of the reasons you are confused is that the interactive mode, by necessity, has to compile incrementally. But compilation of imported modules, and compilation of a main module in non-interactive mode, occurs before any code in that particular module is executed. Please let me know if it's still unclear. Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
