c++ - Template template parameters - extension to std::array -

i have question template template parameters:

let's consider following class:

template<typename t, template<class, class=std::allocator<t> > class underlyingcontainertype = std::vector> class mycontainer { public:     t value1;     t value2;     underlyingcontainertype<t> container;      mycontainer() {}      /* methods implementation goes here */ }; 

in example, mycontainer container chat uses underlying stl-compatible container whatever stuff.

declaring underlying container type template template parameters, instead of regular template argument, allows handy usage of class mycontainer, such as:

    mycontainer<int> mcv; //implicitly using vector     mycontainer<int, std::list> mcl; //no need write std::list<int>                                       //template template parameters 

now, while work of stl-container, such std::vector, std::deque, std::list, , forth, not work, example, std::array provided in c++11.

the reason std::array has different signature of template parameters vector. specifically, are:

std::vector<class t, class allocator = std::allocator<t> > std::array<class t, int n> 

my question if there way generalize class mycontainer, underlying container can std::array well.

i thank in advance.

the commonality between interfaces of vector , array limited element type. container should reflect that:

template<typename t, template<typename> class underlying_container> struct container {     underlying_container<t> storage; }; 

usage requires tiny trick:

template<typename t> using vec = vector<t>; template<typename t> using arr2 = array<t, 2>; 

note vec, unlike vector, has fixed allocator , arr2, unlike array, has fixed size.

usage simple:

container<int, vec> a; container<double, arr2> b; 

see example in action.

alternatively, if prefer match interface used vector, add template alias array instantiates size , adds unused type parameter:

template<typename t, typename> using arr2 = array<t, 2>; 

see in action.