模板的模板参数

先贴下，再回改

#include "pub.h"

template <typename T, template <typename ELEM, typename ALLOC = std::allocator<ELEM> > class CONT = std::deque>
class Stack
{
private:
    CONT<T> elems;

public:
    void push(T const &);
    void pop();
    T top() const;
    bool empty() const
    {
        return elems.empty();
    }

    template<typename T2, template <typename ELEM2, typename = std::allocator<ELEM2> > class CONT2>
    Stack<T, CONT> & operator = (Stack<T2, CONT2> const &);
};

template <typename T, template <typename ELEM, typename >  class CONT>
template<typename T2, template <typename ELEM2, typename > class CONT2>
Stack<T, CONT> & Stack<T, CONT>::operator=( Stack<T2, CONT2> const & op2)
{
    if ( (void *)this == (void *)& op2)
    {
        return *this;
    }

    Stack<T2, CONT2> tmp(op2);
    elems.clear();
    while (!tmp.empty())
    {
        elems.push_front(tmp.top());
        tmp.pop();
    }

    return *this;
}

template <typename T, template <typename ELEM, typename  > class CONT>
T Stack<T, CONT>::top() const
{
    if (elems.empty())
    {
        throw std::out_of_range("empty stack!");
    }

    return elems.back();
}

template <typename T, template <typename ELEM, typename  > class CONT>
void Stack<T, CONT>::pop()
{
    if (elems.empty())
    {
        throw std::out_of_range("empty stack!\n");
    }
    elems.pop_back();
}

template <typename T, template <typename ELEM, typename  > class CONT>
void Stack<T, CONT>::push( T const &elem )
{
    elems.push_back(elem);
}

int main()
{

    return 0;
}