On a simple embedded platform I have no RTTI available but I want to use c++ advantages like inheritance for a class hierarchy like the provided sample. At the moment I'm using the following code snipped to simulate a dynamic cast. To simplify this discussion I ported the code to a simple main.cpp. I used the mingw compiler for testing my sample. The code is working as expected but seams not ideal. I'm not searching for a generic dynamic cast replacement solution considering all aspects. Is there any way to implement this cast with less effort?
class I_BC
{
public:
virtual ~I_BC() {}
virtual int getI_BC() = 0;
};
class I_C
{
public:
virtual ~I_C() {}
virtual int getI_C() = 0;
};
class A
{
public:
virtual ~A() {}
int xx() {return 1;}
template <typename T>
T* cast() { return nullptr;}
protected:
virtual I_BC* cast2BC() {return nullptr;}
virtual I_C* cast2C() {return nullptr;}
};
template <>
I_BC* A::cast<I_BC>() {return this->cast2BC();}
template <>
I_C* A::cast<I_C>() {return this->cast2C();}
class B : public A, public I_BC
{
public:
int getI_BC() override { return 0xB000000C;}
int bar() {return 2;}
protected:
I_BC* cast2BC() override {return this;}
};
class C : public A, public I_BC, public I_C
{
public:
int foo() {return 3;}
int getI_C() override { return 0xC000000C;}
int getI_BC() override { return 0xC00000BC;}
protected:
I_BC* cast2BC() override {return this;}
I_C* cast2C() override {return this;}
};
#include <iostream>
using namespace std;
int main(int argc, char **argv)
{
A* a = new B();
// Ok I know that B implement I_BC interface so cast it now
I_BC* bc = a->cast<I_BC>();
cout << "Res : 0x" << hex << bc->getI_BC() << endl;
}
