[PyQt] sip: extend exception support

[Mathias.Born at gmx.de]

On 26.08.2012, 16:07:52 Phil Thompson wrote:
> On Sun, 26 Aug 2012 14:30:32 +0200, Mathias.Born at gmx.de wrote:
>> On 26.08.2012, 16:46:24 Phil Thompson wrote:
>>> On Wed, 15 Aug 2012 15:54:11 +0200, Mathias.Born at gmx.de wrote:
>>>> ...

> Should all be fixed in current hg and tonight's snapshot.

> Thanks,
> Phil


Ok, I pulled from the hg and could build everything. Quite nifty.
One can now use class instances implemented in python just like
normal C++ without any additional worries.

One issue though. Discussions like

http://www.boost.org/community/error_handling.html

suggest that SIPPyException should be derived from std::exception.
My original suggestion was a bit short-sighted. It would be even
better to let the user define his own exception class.

I'm using sip to embed python code into a Qt/C++ program. Every
exception is reported to the user via a message box:

catch(std::exception const& exc)
{
  QMessageBox(QMessageBox::Critical, "Error", exc.what(), QMessageBox::Ok).exec();
}

With SIPPyException the way it is, I need to add another exception
handler everywhere:

catch(SIPPyException const&)
{
  QMessageBox(QMessageBox::Critical, "Error", pythonExceptionToText(), QMessageBox::Ok).exec();
}

If I could provide a function to call instead of just doing
"throw SIPPyException()", I could throw an exception there myself
as I see fit. For example, there could be a directive

%MethodErrorHandlerCode
  throw std::runtime_error(pythonExceptionToText());
%End

which would follow the %Module directive to define the body of an
error handler function which is called instead of "throw SIPPyException()".

Best Regards,
Mathias