Add/Remove data members with template parameters?

Question

Consider the following code :

template class MyClass
{
    public:
        void myFunction();
        template

        

Answer 1

First off, your code just won't compile for MyClass<false>. The enable_if trait is useful for deduced arguments, not for class template arguments.

Second, here's how you could control members:

template <bool> struct Members { };

template <> struct Members<true> { int x; };

template <bool B> struct Foo : Members<B>
{
    double y;
};

Answer 2

A conditional base class may be used:

struct BaseWithVariable    { int addedVariable; };
struct BaseWithoutVariable { };

template <bool AddMembers> class MyClass
    : std::conditional<AddMembers, BaseWithVariable, BaseWithoutVariable>::type
{
    // etc.
};