template class problem

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This is a portion of my code:

C++

template <class TBase, bool bCalcSize = true>
class COfficeBorder : public TBase
{
protected:

	virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam)
	{
		switch (message)
		{
		case WM_NCPAINT:
			{
				TBase::WindowProc(message, wParam, lParam);

				.
				.
				.

				return 0; // Handled.
			}

		case WM_CREATE:
			{
				if (TBase::WindowProc(message, wParam, lParam) == -1)
					return -1;

				.
				.
				.

				return 0; // Handled.
			}
			break;

		case WM_NCCALCSIZE:
			{
				LRESULT lResult = TBase::WindowProc(message, wParam, lParam);

				.
				.
				.

				return lResult;
			}
		}

		return TBase::WindowProc(message, wParam, lParam);
	}
};

The COfficeBorder works fine with CView, and any other controls:

C++

COfficeBorder<CView>
COfficeBorder<CEdit>
COfficeBorder<CStatic>

Except for CFormView

C++

COfficeBorder<CFormView>

I get the following errors when compiled:

VB

error C2512: 'COfficeBorder<class CFormView,1>' : no appropriate default constructor available
error C2614: 'CTest3View' : illegal member initialization: 'CFormView' is not a base or member

in the constructor:

C++

CTest3View::CTest3View()
    : CFormView(CTest3View::IDD)
{
    //{{AFX_DATA_INIT(CTest3View)
        // NOTE: the ClassWizard will add member initialization here
    //}}AFX_DATA_INIT
    // TODO: add construction code here

}

and the CTest3View class definition:

C++

class CTest3View : public COfficeBorder<CFormView>
{
protected: // create from serialization only
	CTest3View();
	DECLARE_DYNCREATE(CTest3View)

public:
	//{{AFX_DATA(CTest3View)
	enum{ IDD = IDD_TEST3_FORM };
		// NOTE: the ClassWizard will add data members here
	//}}AFX_DATA

// Attributes
public:
	CTest3Doc* GetDocument();

// Operations
public:

// Overrides
	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CTest3View)
	public:
	virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	virtual void OnInitialUpdate(); // called first time after construct
	virtual BOOL OnPreparePrinting(CPrintInfo* pInfo);
	virtual void OnBeginPrinting(CDC* pDC, CPrintInfo* pInfo);
	virtual void OnEndPrinting(CDC* pDC, CPrintInfo* pInfo);
	virtual void OnPrint(CDC* pDC, CPrintInfo* pInfo);
	//}}AFX_VIRTUAL

// Implementation
public:
	virtual ~CTest3View();
#ifdef _DEBUG
	virtual void AssertValid() const;
	virtual void Dump(CDumpContext& dc) const;
#endif

protected:

// Generated message map functions
protected:
	//{{AFX_MSG(CTest3View)
		// NOTE - the ClassWizard will add and remove member functions here.
		//    DO NOT EDIT what you see in these blocks of generated code !
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

Any help here ?

Thank you for your understanding.

Posted 6-Jul-13 9:58am

Mr. Tomay

Updated 6-Jul-13 10:37am

v5

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Comments

smss IR 6-Jul-13 17:35pm

Try with use CFormView as a base class or a member of your own class.

smss IR 6-Jul-13 17:48pm

And see this : http://msdn.microsoft.com/en-us/library/x49xah6k%28v=vs.80%29.aspx

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pasztorpisti · Answer 1 · 2013-07-06T10:21:00

I think the error message is obvious: CFormView doesn't have a default constructor and because of this the automatically generated constructor of your COfficeBorder<CFormView> class has nothing to call. By the way, why COfficeBorder<CFormView> and not COfficeBorder<CTest3View>?

EDIT: Example code for template specialization:

C++

class ControlBase
{
protected:
	virtual void DoSomething() {}
};

class Control1 : public ControlBase
{
public:
	Control1() {}
};


class Control2 : public ControlBase
{
public:
	// no default constructor!!!
	Control2(int param) {}
};


class CommonHelpers
{
public:
	static void DoSomething(ControlBase* b)
	{

	}
};

template <typename BaseControl>
class ControlBorder : public BaseControl
{
protected:
	virtual void DoSomething() override
	{
		CommonHelpers::DoSomething(this);
	}
};

template <>
class ControlBorder<Control2> : public Control2
{
public:
	// We have to call one of the Control2 constructors explicitly because
	// Control2 does not have a default constructor!
	ControlBorder()
		: Control2(2)
	{}
protected:
	virtual void DoSomething() override
	{
		CommonHelpers::DoSomething(this);
	}
};