How to do multiple inheritance for Matlab C++ Mex file?

Dear all,

I would like to generate multiple Mex-Files that all have a similar structure. They all look somethings like this:

class MexFunction : public matlab::mex::Function {
    void operator()(ArgumentList inputs, ArgumentList outputs);
    void doSomeThing();
};

The operator function is always the same, but they all differ in the doSomeThing function. My idea was now to declare a base class like this

class MexBaseFunction : public matlab::mex::Function {
    void operator()(ArgumentList inputs, ArgumentList outputs);
    virtual void doSomeThing() = 0;
};

where I define the common operator() function once and then only change doSomeThing

class MexFunction : public MexBaseFunction {
    void doSomeThing() override;
};

This doesn't work, because in order to define the base class, I have to include mexAdapter.hpp where a lot of stuff is going on that need a class called MexFunction.

My second attempt was to use multiple inheritance by defining a class

class MexBaseFunction {
    void operator()(ArgumentList inputs, ArgumentList outputs);
    virtual void doSomeThing() = 0;
};

that doesn't inherite from matlab::mex::Function. Then my mex-Functions would have the structure

class MexFunction : public matlab::mex::Function, public MexBaseFunction {
    void doSomeThing() override;
};

This doesn't work as well, because I need to include various header files in my base class, because there I need ArgumentList, Struct, CellArray etc. In these header files various functions are defined. In my class that defines MexFunction I need to include the same files and, thus, get errors, because some functions are defined multiple times.

Now my question is:

Is there a proper approach to this problem - are forward-declarations a way to go?

Thanks in advance and best regards,

Torsten

[Manuel Schaich]

I have a similar problem. I assume you have tried to approach this "properly", i.e. you have a separate file MexBaseFunction.cpp and its header which you then compile at the same time and link in... e.g. mex mainSource.cpp MexBaseFunction.cpp -output myMex . This will produce all sorts of bizzare problems revolving around there not being MexFunction::operator() defined. I found that this does not happen while your base class is in the same file as the MexFunction class.

So if you have a header only class as a base class and derive from that you won't see the problems. I find this solution unelegant, but it fixes the problem.

[Torsten Knüppel]

Excellent suggestion, thanks a lot.

[Diego Leal Gonzalez]

I am having exactly the same problem. Have you found another solution to this?