#include <deque>
#include <list>
 
// デフォルトコンストラクタが無い
class A {
public:
    A(int n) : n(n) {}
private:
    int n;
    A(); 
};
 
template <class T, class Container = std::deque<T> >
class stack {
public:
    void push()           { rep.push_back(T()); }
    void push(const T& v) { rep.push_back(v); }
       T top()            { rep.back(); }
    void pop()            { rep.pop_back(); }
private:
    Container rep;
};
 
int main(void) {
    stack<A> s1;
    stack<int> s2;
    stack<A*> s3; // ポリモーフィックな型でもOK
    stack<int, std::list<int> > s4; // 図6.9相当の実装に置換
 
    // デフォルトコンストラクタを必要とするメソッドを呼ばない限りはOK
    //s1.push(); // error!
    s1.push(A(1));
    s1.top();
    s1.pop();
 
    s2.push();
    s2.push(2);  
    s2.top();
    s2.pop();
 
    return 0;
}
 

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