PRB: DDP_PostProcessing() Catches All Exceptions (122273)
The information in this article applies to:
- Microsoft OLE Control Developer's Kit (CDK)
This article was previously published under Q122273 SYMPTOMS
While a custom property page is on display, error messages generated by
ThrowError(), in SetXXXXProperty() methods, will not be displayed.
CAUSE
Error messages generated by ThrowError() are usually displayed by catching
COleDispatchExceptions. The DDP_PostProcessing() function catches all types
of exceptions, preventing COleDispatchExceptions from being caught by the
container application. This means exceptions are caught and ignored as they
are generated while setting a property by using the control's custom
property page.
RESOLUTION
To work around this problem, use a custom DDP_PostProcessing() function
that specifically deals with COleDispatchExceptions thrown by ThrowError().
The sample code in this article builds a sample function called
DDP_PostProcessingEx() based on the original DDP_PostProcessing() function,
but modified to display a message box when a COleDispatchException is
caught. In addition to adding the DDP_PostProcessingEx() function to your
source code, you will also need to include the AFX_DDPDATA structure
definition and constructor in your source file.
To use the new DDP_PostProcessingEx() function, replace the call to
DDP_PostProcessing() with a call to DDP_PostProcessingEx() in your custom
property page's DoDataExchange() function.
STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed
at the beginning of this article. We are researching this problem and will
post new information here in the Microsoft Knowledge Base as it becomes
available.
MORE INFORMATIONSample Code
struct AFX_DDPDATA : public CObject
{
AFX_DDPDATA(LPVOID lpHandler, int nCtrlId, LPVOID lpMember,
UINT nType, LPCTSTR lpszOleName);
LPVOID m_lpHandler;
int m_nCtrlId;
LPVOID m_lpMember;
UINT m_nType;
LPCTSTR m_lpszOleName;
};
AFX_DDPDATA::AFX_DDPDATA(LPVOID lpHandler, int nCtrlId,
LPVOID lpMember, UINT nType, LPCTSTR lpszOleName ) :
m_lpHandler(lpHandler),
m_nCtrlId(nCtrlId),
m_lpMember(lpMember),
m_nType(nType),
m_lpszOleName(lpszOleName)
{
}
void AFXAPI DDP_PostProcessingEx(CDataExchange*pDX)
{
if ( pDX->m_bSaveAndValidate )
{
WORD wKey;
CMapWordToOb &m_DDPmap =((COlePropertyPage*)pDX->m_pDlgWnd)->
m_DDPmap;
AFX_DDPDATA *pDDP = NULL;
POSITION pos = m_DDPmap.GetStartPosition();
while( pos )
{
m_DDPmap.GetNextAssoc( pos, wKey, (CObject *&)pDDP);
TRY
{
switch( pDDP->m_nType )
{
case VT_I1:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
char *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(char *)pDDP->m_lpMember, pDDP->m_lpszOleName);
break;
}
case VT_UI1:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
BYTE *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(BYTE *)pDDP->m_lpMember, pDDP->m_lpszOleName);
break;
}
case VT_I2:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
short *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(short *)pDDP->m_lpMember, pDDP->m_lpszOleName);
break;
}
case VT_UI2:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
WORD *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(WORD *)pDDP->m_lpMember, pDDP->m_lpszOleName);
break;
}
case VT_I4:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
long *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(long *)pDDP->m_lpMember, pDDP->m_lpszOleName);
break;
}
case VT_UI4:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
DWORD *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(DWORD *)pDDP->m_lpMember, pDDP->m_lpszOleName);
break;
}
case VT_R4:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
float *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX, pDDP->m_nCtrlId,
(float *)pDDP->m_lpMember,pDDP->m_lpszOleName);
break;
}
case VT_R8:
{
typedef void (AFXAPI *PFV)(CDataExchange *, int,
double *, LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX,pDDP->m_nCtrlId,
(double *)pDDP->m_lpMember,pDDP->m_lpszOleName);
break;
}
case VT_BSTR:
{
typedef void (AFXAPI *PFV)(CDataExchange *,int,
CString *,LPCTSTR );
(*(PFV)pDDP->m_lpHandler)(pDX,pDDP->m_nCtrlId,
(CString*)pDDP->m_lpMember,pDDP->m_lpszOleName);
break;
}
default:
// Unknown Data Type!
ASSERT(FALSE);
break;
}
}
CATCH(COleDispatchException, e)
{
// display a message box describing caught exception
HWND hWndActive = ::GetActiveWindow();
char szTitle[255];
::GetWindowText(hWndActive, szTitle, sizeof(szTitle));
::MessageBox(hWndActive, (LPCSTR)e->m_strDescription,
szTitle, MB_ICONEXCLAMATION|MB_TASKMODAL|MB_OK);
}
AND_CATCH_ALL(e)
{
// Ignore all other exceptions
}
END_CATCH_ALL
delete pDDP;
}
m_DDPmap.RemoveAll();
}
}
| Modification Type: | Minor | Last Reviewed: | 8/16/2005 |
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| Keywords: | kbcode kbCtrl kbprb kbProgramming KB122273 |
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