how to implement is_pointer?

Question

I want to implement is_pointer. I want something like this:

template 
bool is_pointer( T t )
{
   // implementation
} // return true or fa         


        

Answer 1

template 
struct is_pointer_type
{
    enum { value = false };
};

template 
struct is_pointer_type
{
    enum { value = true };
};

template 
bool is_pointer(const T&)
{
    return is_pointer_type::value;
}

Johannes noted:

This is actually missing specializations for T *const, T *volatile and T * const volatile i think.

Solution:

template 
struct remove_const
{
    typedef T type;
};

template 
struct remove_const
{
    typedef T type;
};

template 
struct remove_volatile
{
    typedef T type;
};

template 
struct remove_volatile
{
    typedef T type;
};

template 
struct remove_cv : remove_const::type> {};

template 
struct is_unqualified_pointer
{
    enum { value = false };
};

template 
struct is_unqualified_pointer
{
    enum { value = true };
};

template 
struct is_pointer_type : is_unqualified_pointer::type> {};

template 
bool is_pointer(const T&)
{
    return is_pointer_type::value;
}

...but of course this is just reinventing the std::type_traits wheel, more or less :)