Template class as a function parameter [C ]-CodePudding

The premise of the question is how to pass a templated class as a parameter to another function or at least get the same effect:

Below is a stripped-down version of my code

template<uint8_t _bus>
class Com {
public:
    uint8_t write() { return _bus; /* does something with template param */}
};


class Instruction
{
public:
    int member;
    void transmitFrame(char *msg) { 
        member = Com.write(msg); /* need to pass in Com object somehow */
    }
};

main(){
    Com<8> myCom;
    Instruction myInstruction;

    char[] msg = {'h', 'e', 'l', 'l', 'o'};
    myInstruction.transmitFrame(msg);
}

The code above will not compile. My first thought would be to just extend the Com class however as far as I am aware you can not extend class templates. My second thought would be to have a template inside a template? (so make the Instruction class a template class with a template of the Com template) But I am in the weeds on that one and not sure if that is possible.

The Com object has been instantiated by the time I am trying to use the Instruction class. So somehow, I need to get the templated Com object into the Instruction class so that I can access it.

At that point I am out of ideas...

CodePudding user response：

You appear to be trying to call write on the Com class directly, rather than an instance.

You likely want to pass an instance of Com to transmitFrame, but to do that you have to pass the template info.

template <uint8_t N>
void transmitFrame(Com<N> &com, char *msg) { 
    com.write(msg); /* need to pass in Com object somehow */
}

Or if you know the template value will be 8.

void transmitFrame(Com<8> &com, char *msg) { 
    com.write(msg); /* need to pass in Com object somehow */
}