#include <memory>

struct A
{
    struct Impl;
    static void deleteImpl(Impl* i);
    std::unique_ptr<Impl, decltype(&deleteImpl)> pimpl;

    A();
};

struct A::Impl
{
    Impl()
    { }

    virtual ~Impl()
    { }

    virtual void foo();
};

struct B : A::Impl
{
    B()
    { }

    virtual void foo() override
    { }
};

void A::deleteImpl(Impl* i)
{
    delete i;
}

A::A()
    : pimpl(new B, &deleteImpl)
{ }

int main()
{
    A a;
}

Fehlermeldungen - Zeilenangaben stimmen nicht ganz da ich nur einen Teil kopiert habe!

/home/ethon/Code/Projekte/Nano/Nano/build> make -j2
[ 75%] Built target nano
Scanning dependencies of target test
[100%] Building CXX object CMakeFiles/test.dir/main.cpp.o
Linking CXX executable test
CMakeFiles/test.dir/main.cpp.o: In function `A::Impl::Impl()':
/home/ethon/Code/Projekte/Nano/Nano/main.cpp:18: undefined reference to `vtable for A::Impl'
CMakeFiles/test.dir/main.cpp.o: In function `A::Impl::~Impl()':
/home/ethon/Code/Projekte/Nano/Nano/main.cpp:21: undefined reference to `vtable for A::Impl'
CMakeFiles/test.dir/main.cpp.o:(.rodata._ZTI1B[_ZTI1B]+0x10): undefined reference to `typeinfo for A::Impl'
collect2: error: ld returned 1 exit status
make[2]: *** [test] Error 1
make[1]: *** [CMakeFiles/test.dir/all] Error 2
make: *** [all] Error 2
*** Fehler: Beendigungscode 2 ***

Vielen Dank & Grüße,
Ethon

virtual void foo() = 0;

?