class UserParamBase : public UserParamName
{
public:
inline UserParamBase() : m_pParent(NULL), m_bCreate(false), m_bLoad(false), m_pParentWnd(NULL) {}
inline UserParamBase(const char* name) : UserParamName(name), m_pParent(NULL), m_bCreate(false), m_pParentWnd(NULL) {}
inline UserParamBase(const UserParamBase&) : m_pParent(NULL), m_bCreate(false), m_pParentWnd(NULL) {} //define the copy constructor so as not to use the default
UserParamBase& operator=(const UserParamBase&) { return *this; } //define the operator= so as not to use the default which would copy a pointer
virtual ~UserParamBase();
void attach(UserParamReg* page);
void PlaceCtrl(UserParamReg* page, CWnd* pParentWnd, const RECT & r, bool bLoad=true);
void CreateCtrl() {create(m_pParentWnd, m_rRegion);};
void CloseCtrl() {close();};
virtual string& value(string& s) = 0;
virtual bool load(const string& s) = 0;
virtual bool readonly() =0;
virtual bool readonly(bool bReadonly) =0;
virtual SIZE winSize() =0;
virtual bool get() =0;
virtual void update() =0;
virtual void create(CWnd* pParentWnd,const RECT& rect) =0;
virtual void close() =0;
inline bool loadable() const { return m_bLoad; }
protected:
virtual void set(bool bAsync=true);
private:
UserParamReg* m_pParent;
bool m_bCreate;
bool m_bLoad;
protected:
RECT m_rRegion;
CWnd * m_pParentWnd;
CritSec m_csWnd;
};
template <class T>
class UserParam : public UserParamB2<T>
{
public:
template <>
class UserParam< string > : public UserParamB2< string >
{
public:
static const LONG labelHeight = 16;
static const LONG controlWidth = 160;
static const LONG controlHeightMultiline = 60;
static const LONG controlHeightSingleline = 18;
static const LONG controlWidthFileButton = 18;
static const bool defaultMultiline = true;
static const bool defaultFileEdit = false;
static const bool defaultReadonly = false;
static const bool defaultAlignRight = false;
enum {nIDFileButton=1000, nIDEdit};
inline UserParam() {}
inline UserParam(const type& t,const char* name=NULL) : UserParamB2<type>(t,name) {}
inline UserParam(const UserParam& t,const char* name=NULL) : UserParamB2<type>(t,name) {}
template <class Y> inline UserParam(const Y& y,const char* name=NULL) : UserParamB2<type>(y,name) {}
inline UserParam& operator=(const UserParam& c) { UserParamB2<type>::operator=(c); return *this; }
bool fileedit(bool bFileEdit) { AutoCritSec acsWnd(m_csWnd, true); return m_wnd.bFileEdit=bFileEdit; }
bool combobox(bool bComboBox=true) { AutoCritSec acsWnd(m_csWnd, true); return m_wnd.bComboBox=bComboBox; }
bool multiline() { AutoCritSec acsWnd(m_csWnd, true); return m_wnd.bMultiline; }
bool multiline(bool bMultiline) { AutoCritSec acsWnd(m_csWnd, true); return m_wnd.bMultiline=bMultiline; }
void addtolist(string str) { AutoCritSec acsWnd(m_csWnd, true); m_wnd.vSelections.push_back(str); fillcombo();}
inline void alignRight(bool bAlignRight) { AutoCritSec acsWnd(m_csWnd, true); m_wnd.bAlignRight = bAlignRight; }
inline bool alignRight(){ AutoCritSec acsWnd(m_csWnd, true); return m_wnd.bAlignRight; }
bool readonly() { AutoCritSec acsWnd(m_csWnd, true); return m_wnd.readonly; }
bool readonly(bool bReadonly)
{
AutoCritSec acsWnd(m_csWnd, true);
if(bReadonly==m_wnd.readonly) return m_wnd.readonly;
if(m_wnd.wnd && m_wnd.wnd->GetSafeHwnd()) {
if(bReadonly) m_wnd.wnd->PostMessage(WM_CANCELMODE);
m_wnd.wnd->PostMessage(WM_ENABLE,(WPARAM)!bReadonly);
}
return m_wnd.readonly=bReadonly;
}
SIZE winSize()
{
SIZE p;
p.cx=controlWidth;
p.cy=labelHeight+((m_wnd.bMultiline && !m_wnd.bComboBox)? controlHeightMultiline : controlHeightSingleline);
return p;
}
//get from control, validate data, set data member if valid;
//return true if data is valid, false otherwise
bool get()
{
AutoCritSec acsWnd(m_csWnd, true);
if(m_wnd.combobox && m_wnd.combobox->GetSafeHwnd()) {
CString text;
m_wnd.combobox->GetWindowText(text);
this->assign((LPCSTR) text);
} else if(m_wnd.wnd && m_wnd.wnd->GetSafeHwnd()) {
//get value from control, set m_d
char* psz=NULL;
unsigned uSize = m_wnd.wnd->GetWindowTextLength()+1;
try {
psz=new char[uSize];
m_wnd.wnd->GetWindowText(psz,uSize);
s.assign(psz);
}
catch(...) {
if(psz) delete [] psz;
throw;
}
if(psz) delete [] psz;
//remove '\r' chars; std::remove returns an iterator to the new .end() position
//use s.erase(..) to erase from this new .end() position through then end of s
s.erase(std::remove(s.begin(),s.end(),'\r'),s.end());
this->assign(s);
}
return true;
}
错误消息如下：
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparam.h(437): error C2259:
'user_param::UserParamB2<std::string>' : cannot instantiate abstract class
due to following members:
'bool user_param::UserParamBase::readonly(bool)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(126) : see
declaration of 'user_param::UserParamBase::readonly'
'bool user_param::UserParamBase::readonly(void)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(125) : see
declaration of 'user_param::UserParamBase::readonly'
'SIZE user_param::UserParamBase::winSize(void)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(127) : see
declaration of 'user_param::UserParamBase::winSize'
'bool user_param::UserParamBase::get(void)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(130) : see
declaration of 'user_param::UserParamBase::get'
'void user_param::UserParamBase::update(void)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(131) : see
declaration of 'user_param::UserParamBase::update'
'void user_param::UserParamBase::create(CWnd *,const RECT &)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(132) : see
declaration of 'user_param::UserParamBase::create'
'void user_param::UserParamBase::close(void)' : is abstract
c:\qc\qc_daq_development\qc\qc_daq\src\hfgui3\userparambase.h(133) : see
declaration of 'user_param::UserParamBase::close'
当我尝试使用覆盖函数覆盖纯虚函数时，没有错误，但最后我得到了很多链接错误lnk2001。请帮我解决这个问题。提前谢谢了。如果我错过了某些内容或者某些内容似乎不清楚，请告诉我。虽然VS 2003再次没有这样的问题，但这种情况在2010年发生。
答案 0 :(得分：0)
抽象类成员函数意味着在派生类中被覆盖。它们的目的是在不提供实现的情况下声明接口。因此，当您在任何类声明中看到类似virtual int foo() = 0;的内容时，这意味着您必须创建派生类并提供foo()实现才能使用此类：
class CBase {
public:
virtual int foo() = 0;
virtual double bar() = 0;
}
class CDerived : public CBase {
public:
virtual int foo(); //no more `= 0` here cause implementation is provided
virtual double bar();
};
int CDerived::foo()
{
return 0;
}
double CDerived::bar()
{
return 0.5;
}
int main()
{
CBase b; //error - abstract class
CDerived d; //ok
}
如果CDerived中有virtual int foo() = 0并且提供函数定义，编译器应该给出错误。 VS2003编译此类代码的事实看起来像是一致性问题。
修改
您的代码中有更多错误。
对于声明为：
的类class UserParamBase : public UserParamName
{
/*...*/
virtual bool readonly();
}
函数定义应为：
bool UserParamBase::readonly()
{
/*...*/
}
很奇怪，readonly（）等代码在您的情况下已成功编译。您将这些函数定义为全局（或命名空间内），因此无法访问受保护的类成员，如m_csWnd。