Call member method of a variadic class template with a member field - c++

Question

I learned a bit about variadic templates and searched over the Internet for some samples and now trying to write some tricky code to call member a method of a variadic class template with one of its fields. I can't understand why it doesn't work. Please, help.
Here is sample classes:
class BarBase
{
public:
BarBase() = default;
virtual void call() = 0;
};
template<typename O, typename M, typename... A>
class Bar
: public BarBase
{
public:
Bar(O* o, M m, A&&... a)
: BarBase()
, m_o(o), m_m(m), m_a(std::forward<A>(a)...)
{ }
void call() override final
{
callInnerWithArgsInside();
}
private:
void callInnerWithArgsInside()
{
(m_o->*m_m)(m_a); // Some errors happends here
}
O* m_o;
M m_m;
std::tuple<typename std::remove_reference<A>::type...> m_a;
};
template<typename O, typename M, typename... A>
BarBase* crateBar(O* o, M m, A&&... a)
{
return new Bar<O, M, A...>(o, m, std::forward<A>(a)...);
}
And call from main:
struct Foo
{
void foo(int ii, float ff, std::string ss)
{
std::cout << "called" << std::endl;
}
};
int main()
{
Foo f;
int i = 10;
float ff = 20.2f;
std::string s = "Hello";
BarBase* bar = crateBar(&f, &Foo::foo, i, ff, s);
bar->call();
}
Errors:
main.cpp
1>d:\drafts_tests\main.cpp(203): error C2198: 'void (__thiscall Foo::* )(int,float,std::string)' : too few arguments for call
1> d:\drafts_tests\main.cpp(202) : while compiling class template member function 'void Bar::callInnerWithArgsInside(void)'
1> with
1> [
1> O=Foo
1> , M=void (__thiscall Foo::* )(int,float,std::string)
1> ]
1> d:\drafts_tests\main.cpp(197) : see reference to function template instantiation 'void Bar::callInnerWithArgsInside(void)' being compiled
1> with
1> [
1> O=Foo
1> , M=void (__thiscall Foo::* )(int,float,std::string)
1> ]
1> d:\drafts_tests\main.cpp(214) : see reference to class template instantiation 'Bar' being compiled
1> with
1> [
1> O=Foo
1> , M=void (__thiscall Foo::* )(int,float,std::string)
1> ]
1> d:\drafts_tests\main.cpp(225) : see reference to function template instantiation 'BarBase *crateBar(O *,M,int &,float &,std::string &)' being compiled
1> with
1> [
1> O=Foo
1> , M=void (__thiscall Foo::* )(int,float,std::string)
1> ]
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

you are passing a tuple to the function, rather than the individual type arguments. The following will pass the required type args to the call:
template<std::size_t... I>
void callInnerWithArgsInside2(std::index_sequence<I...>)
{
(m_o->*m_m)(std::get<I>(m_a)...);
}
void callInnerWithArgsInside()
{
return callInnerWithArgsInside2( std::make_index_sequence<sizeof...(A)>());
}
live demo
EDIT1: C++11 version
I have implemented a C++11 version, see updated live demo