MFnNurbsSurface constructor appears to be private in the C++ API.

[jmreinhart]

I am converting a custom deformer that I wrote using the Python API into C++. One error that I have not been able to resolve is this one.

Error C2248 'Autodesk::Maya::OpenMaya20180000::MFnNurbsSurface::MFnNurbsSurface': cannot access private member declared in class 'Autodesk::Maya::OpenMaya20180000::MFnNurbsSurface' Project3 c:\users\xxx\source\repos\test_node\project3\xxx.cpp 163

I've looked through some similar forum posts and it seems as though this is happening because the constructor for MFnNurbsSurface is private for some reason.  I've updated to the most recent devkit for maya 2018 but that does not resolve it. Is this a known bug, and if so are there any workarounds? Below are what I think are the relevant parts of the code. 

inputSurface = tAttr.create("inputSurface", "is", MFnNurbsSurfaceData::kNurbsSurface);

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MDataHandle inputSurface_data = dataBlock.inputValue(inputSurface, &status);
McheckErr(status, "Error getting inputSurface data handle\n");
MObject inputSurface_val = inputSurface_data.asNurbsSurface();

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MFnNurbsSurface mFnSurface = MFnNurbsSurface(inputSurface_val); <<<THIS IS THE LINE THAT CAUSE THE ERRORS

Any help or insight would be greatly appreciated.

[zewt · Accepted solution]

It's the copy constructor that's private. You're creating an MFnNurbsSurface and then assigning it to another MFnNurbsSurface.  Just initialize it directly, with no copy:

MFnNurbsSurface mFnSurface(inputSurface_val);

That's how you usually want to initialize objects in C++.

[jmreinhart]

Thank you so much. That makes perfect sense and works perfectly. I guess the Autodesk example I had was just very outdated.