Le 2010-07-30 à 1:01, Andrei Alexandrescu a écrit :
> Exception messages are meant to be seen by users.
I disagree.
The error message of an exception might be meaningful in a small program that
does only one thing at a time, but in general to give the user an
understandable error message you need more context information.
For instance, say you have a command line program that takes as input a HTTP
URL and downloads a web page with all its related content. Outputting an error
such as "Socket could not connect to host 1.2.3.4 on port 80: timeout" is quite
cryptic because you don't even know which sub-resource it was trying to fetch,
nor why it fetched that resource (it might be that the HTML parser didn't get
the domain name correctly). And anyway it's probably a bug because it should
just have skipped that resource and went on. If you want to debug that you need
a stack trace to know which resource handler should have caught that exception,
and you might want to attach the debugger to stop when the uncaught exception
is thrown and inspect the circumstances.
And you probably don't want to handle localization inside the exception
handling mechanism either.
Also, for GUI programs an uncaught exception is always a bug because it'll make
the application suddenly quit with no message visible to the user. Exiting a
GUI application with abort() on OSX will ensure that the OS shows an error
message about the application having crashed, and for GUI applications OSX will
save a quite helpful crash report the user can then send to the developer. You
don't want uncaught exceptions to silently quit the application and just be
logged to the system console with no stack trace.
So I believe in the vast majority of cases calling abort() and showing a stack
trace is what you want. That's what most other languages do. It's easy to get
what Andrei wants with a "try {...} catch (Exception e) { writeln(e); exit(-1);
}" in the main, but I'd generally recommend against this.
--
Michel Fortin
[email protected]
http://michelf.com/
_______________________________________________
phobos mailing list
[email protected]
http://lists.puremagic.com/mailman/listinfo/phobos
