How to test whether class B is derived from template family of classes

Question

How to test at compile time whether class B is derived from std::vector?

template
struct is_derived_from_vector {
  static const bool value =          


        

Answer 1

I had the same situation that I needed to know if a class is derived from a vector(like)-class. Unfortunately there is no C++-11 or variadic macros allowed in my project. So my solution was a mixture of Kerrek's answer and this article with some googletest-code at the end:

#include 

template 
class is_derived_from_vector
{
    typedef char Yes_t[1];
    typedef char No_t[2];

    static No_t& test(const void* const);

    template 
    static Yes_t& test(const std::vector* const);

public:
    static const bool value = ((sizeof(test(static_cast(0)))) == (sizeof(Yes_t)));
};

template struct X {};
struct A : X {};
struct B : std::vector {};

TEST(Example, IsDerivedFrom)
{
   EXPECT_FALSE(is_derived_from_vector::value);
   EXPECT_TRUE(is_derived_from_vector::value);
}

A common solution for any templates I think would not be possible to define without usage of C++-11 or higher.