举例
class A从 class IBase，class IProxyBase继承，具体参看后文测试代码。
示意图
测试代码
#include <iostream>
class IBase
{
public:
virtual void FunA() = 0;
virtual void FunB() = 0;
virtual void FunC() = 0;
};
class IProxyBase
{
public:
virtual void ProxyFunA() = 0;
virtual void ProxyFunB() = 0;
virtual void ProxyFunC() = 0;
};
class A : public IBase, public IProxyBase
{
public:
A() :m_nValue(3){
}
virtual ~A(){
}
virtual void FunA() override
{
std::cout << __FUNCTION__ << std::endl;
}
virtual void FunB() override
{
std::cout << __FUNCTION__ << std::endl;
}
virtual void FunC() override
{
std::cout << __FUNCTION__ << std::endl;
}
virtual void ProxyFunA() override
{
std::cout << __FUNCTION__ << std::endl;
}
virtual void ProxyFunB() override
{
std::cout << __FUNCTION__ << std::endl;
}
virtual void ProxyFunC() override
{
std::cout << __FUNCTION__ << std::endl;
}
private:
int m_nValue;
};
int main(int argc, char** argv)
{
A* pA = new A();
std::cout << sizeof(A) << std::endl;
IBase* pBase = pA; //pBase指向pA
IProxyBase* pProxyBase = pA; //pProxyBase指向pA+4, +4是因为此4字节为IBase的虚函数指针大小，参看上文示意图
pBase->FunA();
pProxyBase->ProxyFunA();
//强转后，函数指针指向的还是ProxyFuncA, 所以此处调用的还是ProxyFuncA
reinterpret_cast<IBase*>(pProxyBase)->FunA();
return 0;
}
运行截图
