Subject: "MyBand is Your Band" band object msdn sample unregister problem

if you want to create toolbar/explorer bar in the internet explorer, you have to play with the band objects. MSDN very well explains band object but if you want to study and understand then Paul has written very good article

"MyBand is Your Band: More Reusable MFC Goodies with Band Objects and COMToys" by Paul DiLascia in November 1999. you can find this at msdn site,

http://www.microsoft.com/msj/1199/bandobj/bandobj.aspx

on the xp machine, I found problem while unregistring. it gave me error, and so i couldn't unregister. then i debug the problem and I found issue.

Microsoft provides ICatRegister COM interface to register CATID_InfoBand and CATID_CommBand. With the use of RegisterClassImplCategories and UnRegisterClassImplCategories functions of ICatRegister you
can easily register both the band objects into Internet Explorer registry contexts. The code is also using this interface. Now the problem is code deletes both key tree first and then unregister band object, which fails this UnRegisterClassImplCategories function and return false. if you change sequence, it works fine, here is modified code of UpdateRegistry function,

BOOL CBandObjFactory::UpdateRegistry(BOOL bRegister)
{
BOTRACEFN(_T("CBandObjFactory(%p)::UpdateRegistry(%d)\n"), this, bRegister);

static const LPOLESTR RT_REGISTRY = OLESTR("REGISTRY");
UINT nID = GetResourceID();
if (nID==0)
return TRUE;

if (!::FindResource(AfxGetResourceHandle(),
MAKEINTRESOURCE(nID), CString(RT_REGISTRY)))
return FALSE;

// initialize registry variables
CTRegistrar iReg;
OnInitRegistryVariables(iReg);

// register/unregister script
CString s;
::GetModuleFileName(AfxGetInstanceHandle(),
s.GetBuffer(_MAX_PATH), _MAX_PATH);

USES_CONVERSION;
LPOLESTR lposModuleName = T2OLE(s);
TRACE("sModuleName=%s\n",OLE2T(lposModuleName));

HRESULT hr = bRegister ?
iReg->ResourceRegister(lposModuleName, nID, RT_REGISTRY) :
iReg->ResourceUnregister(lposModuleName, nID, RT_REGISTRY);
if (!SUCCEEDED(hr)) {
TRACE(_T("*** CBandObj:: error %s loading registry script"),DbgName(hr));
return FALSE;
}

// register/unregister categories using ICatRegister
CTCatRegister iCat;
REFIID clsid = m_clsid;
hr = bRegister ?
iCat->RegisterClassImplCategories(clsid, 1, &m_catid) :
iCat->UnRegisterClassImplCategories(clsid, 1, &m_catid);
if (!SUCCEEDED(hr)) {
TRACE(_T("*** CBandObj:: error %s registering categoriy"),DbgName(hr));
return FALSE;
}

/* change sequence, previously it was before ICatRegister code */
if (bRegister==FALSE) {
// IRegistrar doesn't always delete top-level key right, so delete it
CString sClsid;
sClsid = StringFromCLSID(m_clsid);
if (!sClsid.IsEmpty()) { // for extra-safety! don't delete CLSID !!
CString sKey;
sKey.Format(_T("CLSID\\%s"), (LPCTSTR)sClsid);
AfxGetApp()->DelRegTree(HKEY_CLASSES_ROOT, sKey);
}
}

return SUCCEEDED(hr); // return, bypassing MFC/COleObjectFactory
}

Since this code has written in 1999, it was working fine on NT and 98, however i have not checked on 98 or NT. Paul has created really a good framework.