通行證方法

Question

我有一類這樣的

class Keyboard 
{ 
public: 
    Keyboard(void); 
    ~Keyboard(void); 
    void SetHook(HINSTANCE hInstance); 
    LRESULT CALLBACK keyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam); 
}; 


LRESULT CALLBACK Keyboard::keyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam) 
{ 
    bool bControlKeyDown=0; 
    bool caps = GetKeyState(VK_CAPITAL) < 0; 

... 

void Keyboard::SetHook(HINSTANCE hInstance) 
{ 
    KeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, Keyboard::keyboardHookProc, hInstance, NULL); 
} 

但聲明

KeyboardHook = SetWindowsHookEx(WH_KEYBOARD_LL, Keyboard::keyboardHookProc, hInstance, NULL); 

結果在編譯錯誤

Error 7 error C3867: 'Keyboard::keyboardHookProc': function call missing argument list; use '&Keyboard::keyboardHookProc' to create a pointer to member 

如果我更改爲「&鍵盤:: keyboardHookProc'它也錯誤，當我投到'（HOOKPROC）& Keyboard :: k eyboardHookProc」還錯誤

請人幫忙

Answer 1

這是C-回調常見的錯誤。

Keyboard::keyboardHookProc必須是靜態的。

[更新]

，如果你想在static Keyboard::keyboardHookProc上Keyboard對象操作你必須找到一些其他的方式來獲得Keyboard對象這個靜態方法。如果您有一個Keyboard，則可以使用singleton模式。如果不是，則每個靜態方法都必須具有其自己的Keyboard對象。

[UPDATE2]

一個具有全局功能鏈接對象的方式是通過模板對象引用。但是這項工作只適用於全局對象：

class Keyboard 
{ 
public: 
    Keyboard(); 
    ~Keyboard(void); 
    LRESULT keyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam); 
}; 

LRESULT Keyboard::keyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam) 
{ 
} 
// global function interface 
template <Keyboard& k> 
LRESULT CALLBACK keyboardHookProc(int nCode, WPARAM wParam, LPARAM lParam) 
{ 
    return k.keyboardHookProc(nCode, wParam, lParam); 
} 


Keyboard k; // global keyboard 

int main() 
{ 
    // this works 
    SetWindowsHookEx(0, keyboardHookProc<k>, NULL, NULL); 
}