未解析的外部(抽象类构造函数/析构函数)

Question

所以,我有一个抽象类Panel和它的实现MyPanel.他们看起来像这样:

class Panel : public QWidget
{
public:
  Panel(QWidget* parent = 0) = 0;
  virtual ~Panel() = 0;
  // but wait, there's more!!
};

class MyPanel : public Panel
{
public:
  MyPanel(QWidget* parent = 0);
  ~MyPanel() {}; // nothing to do here
};

MyPanel::MyPanel(QWidget* parent) :
  Panel(parent)
{
  // you must construct additional pylons
}

我从VC++中获取构造函数/析构函数的链接器错误

error LNK2019: unresolved external symbol "public: virtual __thiscall Panel::~Panel(void)" (??1Panel@@UAE@XZ) referenced in function "public: virtual __thiscall MyPanel::~MyPanel(void)" (??1MyPanel@@UAE@XZ)  mypanel.obj
error LNK2019: unresolved external symbol "public: __thiscall Panel::Panel(class QWidget *)" (??0Panel@@QAE@PAVQWidget@@@Z) referenced in function "public: __thiscall MyPanel::MyPanel(class QWidget *)" (??0MyPanel@@QAE@PAVQWidget@@@Z)  mypanel.obj

为什么我收到此链接器错误？

---

- - 答案 - -

class Panel : public QWidget
{
public:
  Panel(QWidget* parent = 0) : QWidget(parent) {};
  virtual ~Panel() {};
  // but wait, there's more!!
};

我以为我在午餐前尝试过这个.事实证明我错了.

Answer 1

1. 没有虚拟构造函数这样的东西.
2. 您仍然应该提供析构函数的实现.