error C2259:cannot instantiate abstract class

Question

this is the error message with compiler of visual studio 2010(although it has no problem with compiler of micrsoft visual studio 2003)

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\src\hfgui3\userparambase.h(128) : see declaration of 'user_param::UserParamBase::readonly'
    'bool user_param::UserParamBase::readonly(void)' : is abstract
    c:\qc\qc_daq\src\hfgui3\userparambase.h(127) : see declaration of 'user_param::UserParamBase::readonly'
    'SIZE user_param::UserParamBase::winSize(void)' : is abstract
    c:\qc\qc_daq\src\hfgui3\userparambase.h(129) : see declaration of 'user_param::UserParamBase::winSize'

My source code looks like as follows:

class UserParamBase : public UserParamName
{
    public:
        virtual bool    readonly() =0;
        virtual bool    readonly(bool bReadonly)=0;
        virtual SIZE    winSize()=0;    
        virtual bool    get()=0;
        virtual void    create(CWnd* pParentWnd,const RECT& rect)=0;
        virtual void    close()=0;  
        virtual void    update()=0;
}

...
template <>
class UserParam< string > : public UserParamB2< string >
{
public:
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()) {
        char* psz=NULL;
        string s;
        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;
        s.erase(std::remove(s.begin(),s.end(),'\r'),s.end());
        this->assign(s);
    }
    return true;
}

---

The error message occurs at the this->assign(s); statement.

Answer 1

It's hard to be specific since you did not post any code, only unformatted compiler output. However, it seems that you created a subclass of a class with abstract methods readonly(bool), winSize(void) and you did not implement these functions in subclass. Therefore, your subclass remained abstract. Implement these methods.