c ++ 11中的变量模板和多重继承

Question

i'm trying to achieve something like this:

I have a templated base class which i want to inherit dynamically

template<typename A, typename B>
class fooBase
{
public:
    fooBase(){};
    ~fooBase(){};
};

desired method: (something like this, not really sure how to do it)

template <typename... Interfaces>
class foo : public Interfaces...
{
public:
    foo();
    ~foo();
}

and my goal is to have the foo class act like this:

second method:

class foo()
    : public fooBase<uint8_t, float>
    , public fooBase<uint16_t, bool>
    , public fooBase<uint32_t, int>
    // and the list could go on
{
    foo();
    ~foo();
}

with the second method the problem is that if i instantiate an foo object, it will inherit all the time those 3 base classes, i want to make it more generally and when instantiate a foo object, give it with variadic templates the parameters for the base classes, so that i can use the foo class for other types(maybe will inherit just one base class, maybe five)

Thank you

example for instantiating foo

foo<<uint8_t, float>, <uint16_t, bool>, <uint32_t, int>, /* and the list could go on and on */> instance

Answer 1

Change foo to someting similar to this:

template<typename... Interfaces>
class foo : public Interfaces... {
  public:
    foo(Interfaces... ifaces) : Interfaces(ifaces)... {}

  };

Answer 2

You could try recursive variadic templates, taking 2 arguments at a time to add a derivation from fooBase.

It could be something like:

template<typename A, typename B>
class fooBase
{
public:
    fooBase(){};
    ~fooBase(){};
};

template<typename A, typename B, typename ... C>
class foo: public fooBase<A, B>, public foo<C ...> {
};

// termination version by partial specialization
template<typename A, typename B>
class foo<A, B>: public fooBase<A, B> {
};

You can then declare:

foo<uint8_t, float, uint16_t, bool, uint32_t, int> bar;

and bar will be a subobject of fooBase<uint8_t, float> , fooBase<uint16_t, bool> and fooBase<uint32_t, int>