c++ 变量声明: 成员函数指针 成员变量指针

struct A{
int func(){return 0;}
int val;
};
struct B{
int func(){return 0;}
int val;
};
struct C{
static int A::*pval_A, B::*pval_B;//成员变量的指针(偏移量)
static int (A::*pfunc_A)(), (B::*pfunc_B)();
};
int A::* C::pval_A= &A::val;
int B::* C::pval_B= &B::val;
int (A::*C::pfunc_A)()= &A::func;
int (B::*C::pfunc_B)()= &B::func;

template<typename _Object_Type, typename _Member_Type>
inline _Object_Type& test_max(
_Object_Type& a,
_Object_Type& b,
_Member_Type _Object_Type::* member
){
return a.*member > b.*member? a: b;
}

...
A ta1,ta2;
test_max(ta1, ta2, &A::val);
...