Thread: undefined reference to constructor of parent virtual class

Basically, when the compiler tries to link this stuff into a "simpletest" executable (the simpletest.cpp with a main isn't included but I can if needed) it says it can't reference the constructor of the parent class.

I never call the constructor of the parent class because it's a virtual class, so I am at a loss. Any advice?

Code:

//Device.hpp


class Device
{
public:
        Device();
       virtual DevErrors DevCreateContext(const char*) = 0; 
       virtual void DevDeleteContext() = 0;
       virtual DevErrors DevPrep(Graph **graph, int type) = 0;
       virtual DevErrors DevPrep(Graph **graph, const char *str, int type) = 0;  
       virtual DevErrors DevConfigure(Graph *graph) = 0;
       virtual DevErrors DevInvoke(const DevCallInfo *callinfo, DevGroupFlags flags) = 0;
};


//SimDevice.hpp
#include "Device.hpp"
class SimDevice : public Device
{
public:
        SimDevice();
        DevErrors DevCreateContext(const char*);
        void DevDeleteContext();
        DevErrors DevPrep(Graph **graph, int type);
        DevErrors DevPrep(Graph **graph, const char *str, int type);
        DevErrors DevConfigure(Graph *graph);
        DevErrors DevInvoke(const DevCallInfo *callinfo, DevGroupFlags flags);
        ~SimDevice();
private:
        DevContextInfo info;
        DevContextResult result;


};


//SimDevice.cpp
#include "SimDevice.hpp"
SimDevice::SimDevice() // Compiler is saying this line has undefined reference to `Device::Device()'
{
    /* Do constructor stuff. */
}

When constructing an object, its base class ctor is called, too. By having the following line in class Device you promise to define your own ctor, but you never do. Just take it out if you don't want to define one.

Code:

       Device();

My guess is

Replace

Code:

Device();

with

Code:

Device(){;}

Note: I have yet to learn C++

Tim S.

Originally Posted by joshuastuden

DO you really think you can just remove a constructor definition like that? lol.

Have you never heard of a default constructor?

Code:

#include <iostream>
 
class Base {
public:
    virtual void func() = 0;
    virtual ~Base() {}
};
 
class Derived : public Base {
    int n;
public:
    Derived(int n) : n(n) {}
    ~Derived() {}
    void func() { std::cout << "func: " << n << '\n'; }
};
 
int main() {
    Base *b = new Derived(42);;
    b->func();
    delete b;
}