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Re: Making C++ objects persistent between mex calls, and robust.
Posted:
Nov 7, 2012 12:19 PM
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Dear Oliver,
first of all, thank you very much for writing the initial coincise and clear post. I was searching in google for this problem and reading this thread helped me very much.
Indeed, I managed to interface my C++ class with MATLAB defining a class derived from "handle" in MATLAB and then using new/delete and the convertMat2HandlePtr / convertPtr2Mat methods in C++ .
Just a suggestion: why don't you create a FileExchange contribution with the C++ code and the MATLAB class wrapper? I think it would be very useful to anybody tackling this same issue! :)
Finally, a question about mexLock() and mexUnlock() usage suggested in the last post: it doesn't work for me: mexLock() gets called in convertPtr2Mat() in the init_mex() MEX file, so that it will lock the "init_mex resource", but then mexUnlock() gets called in destroyObject() which is located in the clear_mex() MEX file, and will try to unlock the "clear_mex resource", which is already unlocked. Most important since the mexUnlock() call is located in a different MEX file, the one which called mexLock() will remain locked forever...
did I miss something?
do you implement the clear_mex() and init_mex() functions in the same MEX file? if so, how do you do that (as far as I know, there is only one mexFunction() possible in each MEX file)...
Thank you very much!
Francesco
>
> template<class base> inline class_handle<base> *convertMat2HandlePtr(const mxArray *in)
> {
> if (mxGetNumberOfElements(in) != 1 || mxGetClassID(in) != mxUINT64_CLASS || mxIsComplex(in))
> mexErrMsgTxt("Input must be a real uint64 scalar.");
> class_handle<base> *ptr = reinterpret_cast<class_handle<base> *>(*((uint64_t *)mxGetData(in)));
> if (!ptr->isValid())
> mexErrMsgTxt("Handle not valid.");
> return ptr;
> }
>
> template<class base> inline base *convertMat2Ptr(const mxArray *in)
> {
> return convertMat2HandlePtr<base>(in)->ptr();
> }
>
> template<class base> inline void destroyObject(const mxArray *in)
> {
> delete convertMat2HandlePtr<base>(in);
> mexUnlock();
> }
>
> // Code for init_mex() - ISM3D is my C++ object class, but you use your own
> ISM3D *ism = new ISM3D(var1, var2);
> plhs[0] = convertPtr2Mat<ISM3D>(ism);
>
> // Code for clear_mex()
> destroyObject<ISM3D>(prhs[0]);
>
> // Code for action_mex
> ISM3D *ism = convertMat2Ptr<ISM3D>(prhs[0]);
> ism->action();
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