定制容器要求与Qt的foreach一起使用

Question

创建可与Qt foreach宏一起使用的自定义容器的最小代码量是多少？

到目前为止我有这个

template< class T >
class MyList
{
public:
  class iterator
  {
  public:

  };
  class const_iterator
  {
  public:
    inline iterator& operator++ ()
    {
      return *this;
    }
  };
};

我收到这个编译器错误:

4>.\main.cpp(42) : error C2100: illegal indirection
4>.\main.cpp(42) : error C2440: 'initializing' : cannot convert from 'MyList<T>::const_iterator' to 'int'
4>        with
4>        [
4>            T=int
4>        ]
4>        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

当我尝试编译这个:

  MyList<int> mylst;
  foreach(int num, mylst )
    qDebug() << num;

Answer 1

我省略了我使用的虚拟实现,但这是为我编译的:

template< class T >
class MyList
{
public:
    class const_iterator
    {
    public:
        const T& operator*();
        bool operator!=( const const_iterator& ) const;
        const_iterator& operator++();
    };

    const_iterator begin() const;
    const_iterator end() const;
};