Search code examples
c++templatesboostboost-mpl

Detecting at compile-time whether a class has a member variabe or function

I'm trying to detect at compile time whether a class Foo or Bar has either the variable value or member variable initValue().

struct Foo
{
    static const int value;
    static int initValue();
};

struct Bar
{
};

I've found several boost and boost MPL classes and utils such as BOOST_MPL_HAS_XXX_TRAIT_DEF and valid_member_metafunction that appear to do just this but am unsure which to use. I know it's possible to roll out my own detector but I'd rather not.

Solution

  • Found it. has_static_member_data and has_static_member_function from the Boost TTI library.

    #include <boost/tti/has_static_member_data.hpp>
BOOST_TTI_HAS_STATIC_MEMBER_DATA( value ) // Generates class template has_static_member_data_value
...
has_static_member_data_value<Foo, int>::value;  // returns true
has_static_member_data_value<Bar, int>::value;  // returns false