#include <iostream>

struct MyInterface
{
    virtual void    UpdateValue(int vl) = 0;
    virtual int     CallTwo(int a) = 0;
};

struct Data
{
    int value{};
};

struct InterfaceMemory
{
    size_t* vtable = nullptr;
    Data data{};
};

void FuncCall(InterfaceMemory* memory, int vl)
{
    memory->data.value = vl;
}

int FuncTwo(InterfaceMemory* memory, int a)
{
    return memory->data.value + a;
}

int main()
{

    InterfaceMemory memory{};

    memory.vtable = (size_t*)malloc(sizeof(size_t) * 2);
    memory.vtable[0] = (size_t)FuncCall;
    memory.vtable[1] = (size_t)FuncTwo;

    MyInterface* interface = reinterpret_cast<MyInterface*>(&memory);

    interface->UpdateValue(20);
    int res = interface->CallTwo(30);

    std::cout << "res " << res << std::endl;

    return 0;
}