c++ - Template function on struct members -


is there way code single template function able run on different members of given struct ?

a wrong example : 

struct foo {   int a, b; }  template <member x> //which not exist  cout_member(foo foo) {   cout << foo.x << endl; }  int main() {   foo foo;    cout_member<a>(foo);   cout_member<b>(foo);   return 0; }

i imagined answer based on switch, wondered if switch tested on run-time (what avoid) or on compile-time ?

as long want pick data member set of data members having same type, can use pointer data member:

template <int foo::*m> void cout_member(foo foo) {     std::cout << (foo.*m) << std::endl; }

and use as:

cout_member<&foo::a>(foo);

if want indicate type, can this:

template <typename t, t foo::*m> void cout_member(foo foo) {     std::cout << (foo.*m) << std::endl; }

and use as:

cout_member<int, &foo::a>(foo);

just out of curiosity, second snippet simpler in c++17:

template <auto m> void cout_member(foo foo) {     std::cout << (foo.*m) << std::endl; }

see , running on wandbox;


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