member-pointers

I try to compile the following with g++ 4.7.2: template <typename T> struct A { struct B { T t; template<T B::*M> T get() { return this->*M; } }; B b; T get() { return b.get<&B::t>(); } }; int main() { A<int> a; a.get(); } It gives me test.cpp: In member function ‘T A<T>::get()’: test.cpp:15:23: error: expected primary-expression before ‘)’ token test.cpp: In instantiation of ‘T A<T>::get() [with T = int]’: test.cpp:22:8: required from here test.cpp:15:23: error: invalid operands of types ‘<unresolved overloaded function type>’ and ‘int A<int>::B::*’ to binary ‘operator<’ Why? Thanks. You need

The following code yields a compile time error: ' base::print ' : cannot access private member declared in class ' base_der ' However, I have made the member public in the derived class. Why doesn't this work? #include <iostream> using namespace std; class base { public: int i; void print(int i) { printf("base i\n"); } }; class base_der : private base { public: using base::print; }; int main() { // This works: base_der cls; cls.print(10); // This doesn't: void (base_der::* print)(int); print = &base_der::print; // Compile error here } I think there are a few interacting problems contributing

I have a problem regarding member pointers. The following code fails to compile using both Oracle Solaris Studio 12.2's CC and cygwin GCC 4.3.4 but works with Microsoft Visual C++ 2010: struct A { int x; }; struct B : public A { }; template<typename T> class Bar { public: template<typename M> void foo(M T::*p); }; int main(int, char *[]) { Bar<B> bbar; bbar.foo(&B::x); return 0; } At the next to last line both compilers mentioned above fail to find a match for Bar<B>::foo(int A::*) . I wrote a simple test to confirm that the type of the expression &B::x is actually int A::* : // ... static

The foolowing reduced code sample does not do anything usefull but two subsequent assignments to a data member pointer. The first assignement works, the second one gives a compiler error. Presumably because its to a nested member. Question would be: Is it really just not possible to let a member pointer point to a nested member or am I missing any fancy syntax there? struct Color { float Red; float Green; float Blue; }; struct Material { float Brightness; Color DiffuseColor; }; int main() { float Material::* ParamToAnimate; ParamToAnimate = &Material::Brightness; // Ok ParamToAnimate =

template<class T, typename U> ptrdiff_t foo(T U::* m) { // return offset } How I can get the offset of the field 'm' in this context? I would prefer to use am compile-time expression. Thanks in advance for any help. Best regards Sounds like you're looking for the offsetof() macro. @Michael J Thanks for your answer. This wasn't exactly what I was looking for, but it gives me the inspiration to doing that: template<class T, typename U> std::ptrdiff_t member_offset(U T::* member) { return reinterpret_cast<std::ptrdiff_t>( &(reinterpret_cast<T const volatile*>(NULL)->*member) ); } The simple

We all know members specified protected from a base class can only be accessed from a derived class own instance. This is a feature from the Standard, and this has been discussed on Stack Overflow multiple times: Cannot access protected member of another instance from derived type's scope ; Why can't my object access protected members of another object defined in common base class? And others. But it seems possible to walk around this restriction with member pointers, as user chtz has shown me : struct Base { protected: int value; }; struct Derived : Base { void f(Base const& other) { //int n