CODEWITHSUNDEEP
c++mfcview
Itban Saeed
Itban Saeed

Reputation: 1666

Calling UpdateAllViews with a CString parameter

I need to call the CDocument::UpdateAllViews method with following parameters:

One way, described in MSDN documentation is to pass a CObject derived class and override the CView::OnUpdate member function in the CView-derived class.

Is there any other way I can do that?

Upvotes: 1

Views: 469

Answers (1)

xMRi
xMRi

Reputation: 15375

No there isn't! Because the last parameter of UpdateAllViews needs a pointer to an object and a CString is not derived from CObject you need to wrap the string inside a class derived from CObject:

class CMyHint : public CObject
{
public: 
    CString m_strHint;
};

...
CMyHint hint;
hint.m_strHint = _T("hint");
UpdateAllViews(nullptr,0,&hint);
...

void CMyView::OnUpdate(CView* pSender, LPARAM lHint, CObject* pHint)
{
    CMyHint *pMyHint = static_cast<CMyHint*)(pHint);
    CString str = pMyHint->m_strHint;
...

Edit: I just looked into the source code of the MFC. The CObject *pHint is nowhere used between CDocument::UpdateAllViews and CView::OnUpdate. So the pointer is never used as an CObject.

So it is possible (but I would not recommend it), that you use reinterpret_cast<CObject*> to a pointer to a CString and later in CView you use reinterpret_cast<CString*> to get the string pointer again.

Possible but again: I would not recommend it!

Upvotes: 1

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