On Wed, 15 Aug 2012 15:54:11 +0200, mathias.b...@gmx.de wrote:
> Phil,
>
> sip can already propagate C++ exceptions into Python in cases
> where Python calls a C++ function which throws an exception.
>
> However, if I extend a C++ class in Python and call a corresponding
> (Python-)method in C++ via the wrapper, the sip generated
> wrapper code checks for a Python exception, but doesn't throw an
> excpetion itself.
> For example:
>
> ========= <code generated by sip> =======================
> boost::optional<int> sipVH_ltse_app_0(sip_gilstate_t
sipGILState,PyObject
> *sipMethod,const std::string& a0)
> {
> boost::optional<int> sipRes;
> PyObject *resObj = sipCallMethod(0,sipMethod,"N",new
> std::string(a0),sipType_std_string,NULL);
>
> if (!resObj ||
>
sipParseResult(0,sipMethod,resObj,"H5",sipType_boost_optional_1800,&sipRes)
> < 0)
> PyErr_Print();
>
> Py_XDECREF(resObj);
> Py_DECREF(sipMethod);
>
> SIP_RELEASE_GIL(sipGILState)
>
> return sipRes;
> }
> =========================================================
>
> Here, "PyErr_Print" is called if the Python implementation of
> the method raises an exception. This is fine for Qt which
> cannot deal with exceptions, but in general I would find it
> much more helpful if the wrapper code generated by sip
> threw a C++ exception itself to signal the problem to the
> caller.
>
> Just define a class, e.g. "SIPPyException" (derived from
> std::exception), which becomes part of the API and is always used
> in such cases.
> In order not to break existing code, it would only be used in
> classes or methods which are annotated appropriately.
> (So an additional annotation is necessary to activate this behavior.)
>
> I believe an extension like this would make sip a lot more useful
> for embedding Python into a C++ program.
>
> Best Regards,
> Mathias Born
Try current hg or tonight's snapshot. See the all_throw_cpp_exception
%Module argument and the /ThrowsCppException/ and /NoThrowsCppException/
function annotations.
Not heavily tested.
Phil
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