包含了头文件编译的时候却报错，说类型为定义
#include <list>
#include <queue>
#include "DataSource.h"
using namespace std;
class BufferObserver
{
public:
virtual ~BufferObserver();
virtual void notify();
virtual void attach(DataSource & source);
private:
list<DataSource> mList;
};
#include "Demuxer.h"
#include <queue>
using namespace std;
class DataSource
{
public:
DataSource() { };
...
}
