On Mon, 3 Sep 2012 22:27:41 +0200, mathias.b...@gmx.de wrote:
> Hi Phil,
>
> I've come across a case which I think deserves its own function
annotation.
> This is the proplem:
>
> I'm embedding Python code into a C++ app. There are two wrapped classes:
>
> class Netlister
> {
> virtual ~Netlister();
> ...
> };
>
> and
>
> class Project
> {
> virtual ~Project();
> ...
> virtual NetLister* netLister(const std::string& netListText)
const;
> };
>
> In Python, I have ("ltse_app" is the C++ app exposed as module)
>
>
> class LTspiceNetLister(ltse_app.NetLister):
> ...
>
> and
>
> class Project(ltse_app.Project):
> ...
> def netLister(self, netListText):
> return LTspiceNetLister()
>
>
> First, I call a Python function which gives me an instance of the Python
> class "Project". Then (in C++, using its wrapper), I call its method
> "netLister",
> which returns an instance of "LTspiceNetLister". The goal is to use
> this instance on the C++ side via its wrapper. Thus, ownership should be
> with C++.
>
> But there is no corresponding annotation for the sip file. I have to
> provide
> a "%VirtualCatcherCode":
>
> virtual NetLister* netLister(const std::string& netListText /NoCopy/)
> const;
> %VirtualCatcherCode
> PyObject *resObj = sipCallMethod(0, sipMethod, "D",
> const_cast<std::string*>(&a0), sipType_std_string, NULL);
> sipIsErr = !resObj || sipParseResult(0, sipMethod, resObj, "H0",
> sipType_NetLister, &sipRes) < 0;
> if (!sipIsErr) sipTransferTo(resObj, Py_None);
> Py_XDECREF(resObj);
> %End
>
> Note how I use "sipTransferTo(resObj, Py_None);" to bind the Python
object
> to the C++ instance.
> I'm basically asking for something like the "Factory" annotation which
> does just that.
>
> "Factory" tells sip that a wrapped C++ function creates a new object
that
> will be owned by the
> Python side. I'd like to have another annotation which tells sip that
the
> Python implementation
> of a class method creates a new object that will be owned by the C++
side.
The documentation for /Factory/ is wrong (now fixed in hg). It effectively
does...
sipTransferTo(resObj, selfObj);
...in the virtual catcher (where selfObj) is the class's self object (the
Project instance in this case). You are using Py_None but I don't think it
would make a difference.
Would this remove your use case for sipTransfer(obj, Py_None)?
Phil
_______________________________________________
PyQt mailing list PyQt@riverbankcomputing.com
http://www.riverbankcomputing.com/mailman/listinfo/pyqt
