[PyQt] Exceptions in Python Implementations of Virtuals

[Phil Thompson]

On 01/10/2014 10:03 am, Florian Bruhin wrote:
> * Phil Thompson <phil at riverbankcomputing.com> [2014-10-01 09:31:26 
> +0100]:
>> On 01/10/2014 9:05 am, Florian Bruhin wrote:
>> >* Phil Thompson <phil at riverbankcomputing.com> [2014-10-01 08:53:10 +0100]:
>> >>Of course qFatal() only aborts the application if you are using the
>> >>default
>> >>message handler. There is nothing to stop you doing exactly what you
>> >>would
>> >>do with sys.excepthook and you would also catch any calls from within
>> >>Qt.
>> >
>> >If this can easily be overrided by setting sys.excepthook, big +1 for
>> >it from me.
>> >
>> >Applications with a custom exception handler won't break, and
>> >applications without a handler (which are already broken) will fail
>> >loudly rather than silently, just like anything else in Python.
>> >
>> >Still I think qFatal should be used (even when sys.excepthook is set)
>> >in the few places known to cause segfaults otherwise. An exception
>> >message and qFatal is still better than a segfault without any message
>> >(and random coredump).
>> 
>> So...
>> 
>> For all exceptions raised by virtual reimplementations (and slots 
>> connected
>> to signals) PyQt will invoke an error handler that will check if
>> sys.excepthook has been modified. If it has been modified then it does
>> nothing, otherwise it calls qFatal(). That should mean that "good"
>> applications continue to work without changes.
>> 
>> It will be possible to specify (in the .sip file) that an individual 
>> virtual
>> must not raise an unhandled exception. This would be implemented by
>> explicitly calling abort() after calling the error handler.
> 
> Sounds perfect to me.
> 
> What version do you plan to add this to? IMHO this is something which
> could be added to a minor version (as said - good applications will
> continue to work), but I also see why such a big change wouldn't be
> added to a minor release.

The next release is likely to be v5.4 anyway.

Phil