Hi,
I have a function init_logging.log_uncaught_errors() that I use for
sys.excepthook. Now I also want to call another function (ffi.dlclose())
upon abnormal termination. Is it possible to register multiple
excepthooks, like with atexit.register? Or should I rename/redefine
log_uncaught_errors() so it does both things?
Thanks!
Albert-Jan

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Albert-Jan,

Unless there is something special in your scenario, aren't there many ways within python proper to create functions that effectively call another
function or more as needed? Think decorators as one example.

Of course if the caller expects some specific result when it calls your function, running a single function that returns say the value of the last thing it does, may not meet your needs.

Now assuming all your functions take the same required argument and do not
in any way tamper with the argument, you could indeed define a function that accepts arguments and internally calls one after another other functions in some order and intercepts anything they return (or errors) and consolidates them as needed and returns a result. I suspect there is a module that
provides such functionality.




-----Original Message-----
From: Python-list <python-list-bounces+avi.e.gross=gmail.com@python.org> On Behalf Of Albert-Jan Roskam
Sent: Sunday, July 31, 2022 5:40 AM
To: Python-list@python.org
Subject: Register multiple excepthooks?

Hi,
I have a function init_logging.log_uncaught_errors() that I use for
sys.excepthook. Now I also want to call another function (ffi.dlclose())
upon abnormal termination. Is it possible to register multiple
excepthooks, like with atexit.register? Or should I rename/redefine
log_uncaught_errors() so it does both things?
Thanks!
Albert-Jan
--
https://mail.python.org/mailman/listinfo/python-list

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Albert-Jan Roskam wrote at 2022-7-31 11:39 +0200:

I have a function init_logging.log_uncaught_errors() that I use for
sys.excepthook. Now I also want to call another function (ffi.dlclose())
upon abnormal termination. Is it possible to register multiple
excepthooks, like with atexit.register? Or should I rename/redefine
log_uncaught_errors() so it does both things?

`sys.excepthook` is a single function (not a list of them).
This means: at any moment a single `excepthook` is effective.

If you need a modular design, use a dispatcher function
as your `excepthook` associated with a registry (e.g. a `list`).
The dispatcher can then call all registered function.

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On Aug 1, 2022 19:34, Dieter Maurer <dieter@handshake.de> wrote:

Albert-Jan Roskam wrote at 2022-7-31 11:39 +0200:
>   I have a function init_logging.log_uncaught_errors() that I use for
>   sys.excepthook. Now I also want to call another function
(ffi.dlclose())
>   upon abnormal termination. Is it possible to register multiple
>   excepthooks, like with atexit.register? Or should I rename/redefine
>   log_uncaught_errors() so it does both things?

`sys.excepthook` is a single function (not a list of them).
This means: at any moment a single `excepthook` is effective.

If you need a modular design, use a dispatcher function
as your `excepthook` associated with a registry (e.g. a `list`).
The dispatcher can then call all registered function.

====
Thank you both. I'll give this a try. I think it would be nice if the
standard library function atexit.register would be improved, such that the
registered functions would not only be called upon (a) normal program
termination, but that one could also register functions that are called
(b) upon error (c) unconditionally. Much like (a) try - (b) except - (c)
finally.

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On 2022-08-04 at 09:41:00 +0200,
Albert-Jan Roskam <sjeik_appie@hotmail.com> wrote:

Thank you both. I'll give this a try. I think it would be nice if
the standard library function atexit.register would be improved,
such that the registered functions would not only be called upon
(a) normal program termination, but that one could also register
functions that are called (b) upon error (c) unconditionally. Much
like (a) try - (b) except - (c) finally.

There. You've just designed the top level of a better behaved, more
robust application (completely untested):

on_normal_exit_funcs = list()
on_error_exit_funcs = list()
on_any_exit_funcs = list()

def run_exit_funcs(exit_funcs):
for func in exit_funcs:
try: func()
except e: maybe_do_some_logging(e)

try:
run_the_application()
run_exit_funcs(on_normal_exit_funcs)
except:
run_exit_funcs(on_error_exit_funcs)
finally:
run_exit_funcs(on_any_exit_funcs)

def register_normal_exit_func(f):
on_normal_exit_funcs.append(f)

def register_error_exit_func(f):
on_error_exit_funcs.append(f)

def register_any_exit_func(f):
on_any_exit_funcs.append(f)

No, really. There are worse ways to build an extremely generic, fairly minimalist application framework.

Season to taste,¹ add it to your personal (or company) toolbox, and
refine and improve it as things come up. You may discover some number
of common exit functions that are useful across appliations, too.

¹ are you object oriented, functional, imperative, or something else?
do you like long names, short names, names that follow some existing
coding standard, non-English names? do you have a standardized logging/exception library?

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