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interface INishFirst : IDispatch
{
[id(1), helpstring("method GetString")] HRESULT GetString([in] BSTR* pbstrInString, [out,retval] BSTR* pbstrOutString);
[id(2), helpstring("method GetArray")] HRESULT GetArray([out,retval] BSTR** pbstrArray);
};
It's showing an error :-
warning MIDL2039 : interface does not conform to [oleautomation] attribute : [ Parameter 'pbstrArray' of Procedure 'GetArray' ( Interface 'INishFirst' ) ]
Am I not allowed to have BSTR **s????
My most recent CP article :-
A newbie's elementary guide to spawning processes
www.busterboy.org
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BSTR is already a pointer. So BSTR** is a "triple pointer" (omg!  ), which of course is not supported by automation.
From MSDN:
typedef OLECHAR FAR* BSTR;
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You can have BSTR **, so long as you don't want your COM object to be Automation-compatible (ie usable in ASP). The Automation type standard is quite strict on this sort of thing.
------------------------
Derek Waters
derek@lj-oz.com
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I might want to add:
- use BSTR for your [in] param
- use BSTR* for your [out] param
Edit: fixed the little bug in my 2nd statement 
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Derek Waters wrote:
You can have BSTR **, so long as you don't want your COM object to be Automation-compatible (ie usable in ASP). The Automation type standard is quite strict on this sort of thing.
Thanks again Derek. I jus found that out 
Nish
My most recent CP article :-
A newbie's elementary guide to spawning processes
www.busterboy.org
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Nish [BusterBoy] wrote:
I was just advised to use BSTR* as my out parameters
I meant to say that actually, must be smoking crack...
Sorry for the confusion
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Just some more information...
The OLE Automation restriction is there for a reason. The idea is that if an interface supports OLE automation no external proxy code is required to marshal the calls.
I leave it to the reader to translated what I just said into English. I know for the longest time I had NO CLUE what any of that ment. (Heh, and I hope I got the statement right.)
Tim Smith
I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?
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Nish,It's also nice to use _bstr_t,it encapsulate the BSTR
data type.It manages resource allocation and deallocation through internall calls
to SysAllocString() and SysFreeeStrnig so you don't have to add
these function to your code.It provides a number of operators that enable you to use a
_bstr_t object as easily as you would use a CString.But one thing
that isn't provide,is the & "address of" operator,so can't pass the address of
a _bstr_t to a function that expects a BSTR *.
Hope that helps.
Mazy
"So,so you think you can tell,
Heaven from Hell,
Blue skies from pain,...
How I wish,how I wish you were here."
Wish You Were Here-Pink Floyd-1975
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I am writing codes to put a view in a dialog.
Here are the code to initialize the view in a dialog:
BOOL CMyDialog::OnInitDialog()
{
CDialog::OnInitDialog();
CCreateContext pContext;
CWnd* pFrameWnd = this;
pContext.m_pCurrentDoc = new CMyDoc();
pContext.m_pNewViewClass = RUNTIME_CLASS(CMyView);
CMyView *pView = (CMyView *) ((CFrameWnd*)pFrameWnd)->CreateView(&pContext);
ASSERT(pView);
pView->ShowWindow(SW_NORMAL);
CRect rectWindow;
GetWindowRect(rectWindow);
ScreenToClient(rectWindow);
rectWindow.right += 15;
rectWindow.top -= 10;
pView->MoveWindow(rectWindow);
return TRUE;
}
I got two problems:
(1) If the CMyView is kind of CHtmlView and if the dialog is displayed within an MFC MDI application, when I clicked the view right after the view is displayed, I got an ASSERT in CView::OnMouseActivate(..). But if the dialog is the main window of a dialog-based MFC app, it works fine. Why?
(2) I use the following code to detect if there is memory leak:
void CMyDlgView::OnViewViewInDialog()
{
#ifdef _DEBUG
CMemoryState oldMemState, newMemState, diffMemState;
oldMemState.Checkpoint();
#endif
ShowDialog();
#ifdef _DEBUG
newMemState.Checkpoint();
if( diffMemState.Difference( oldMemState, newMemState ) )
{
TRACE( "Memory leaked!\n" );
}
#endif
}
void CMyDlgView::ShowDialog()
{
CMyDialog dlg;
dlg.DoModal();
}
if it is a CHtmlView derived view, there is memork leak; however if it is a generic CView derived view, no memory leak. Why?
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It is this that got me thinking:
((CFrameWnd*)pFrameWnd)->CreateView(...) If I'm understading your code, pFrameWnd is a CDialog and not a CFrameWnd. My guess it that this works (when it does) due to pure chance, and it's no wonder weird things happen afterward. Maybe you can take a look at the source code of CFrameWnd::CreateView to try to determine what's going wrong.
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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I have tried other method to create a view using something like:
CView *pView = pRuntimeClass->CreateObject();
pView->Create(...);
It got the same assert. However if I add (Overide) a message handler of OnMouseActive(..)of CMyView and just call CWnd::OnMouseActivate(..) within that handler, the ASSERT goes away. Odd!
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One of the problems I've come across when using the CMemoryState items is that they tend to take an exact snapshot of memory. Good for some things, bad for others. It showed a memory leak in my code that was really just the fact that I took the snapshot before initializing an array and then comparing it to the array after it was freed and set to empty at the end of the function. The 'leak' went away if I took the snapshot after I did a memset to initialize the array instead of before. My guess is that the class initializes some structures and the difference is shown as a leak. If you use a trial version of one of the other memory checkers (BoundsChecker, Insure, etc...) then it might help determine if it's a real leak.
Good luck with the project.
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Anonymous wrote:
My guess is that the class initializes some structures and the difference is shown as a leak. If you use a trial version of one of the other memory checkers (BoundsChecker, Insure, etc...) then it might help determine if it's a real leak.
Thanks a lot. Your argument is what I have been suspecting. I would try other memory check programs for this example. Hope you are right.
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Have you included <tchar.h>?
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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My guess is I can't do this stuff on Win 98!!!
You can write Unicode stuff in Win98, altough you might not be able to run it (I've written Unicode things in Win95). The problem must lie elsewhere. Is TEXT also undefined?
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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Joaquín M López Muñoz wrote:
The problem must lie elsewhere. Is TEXT also undefined?
Yes. I believe the problem lies elsewhere [actually I have a guess as to the "elsewhere"]
I got an error message [actually a warning] that the unicode dll could not be loaded. So for some strange reason my Win 98 does not support unicode
Nish
My most recent CP article :-
A newbie's elementary guide to spawning processes
www.busterboy.org
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Nish [BusterBoy] wrote:
So for some strange reason my Win 98 does not support unicode
Windows 3/95/98/ME do not support unicode, Windows NT/2k/XP do.
- Matt Newman
-Sonork ID: 100.11179:BestSnowman
Frankly AOL should stick to what it does best: Fooling millions of americans into believing that it, AOL, is the web. -Paul Watson
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MFC v6 unicode DLLs will NOT load on the 9x platforms.
If you really want to do Unicode on 9x, you can use MSLU (a.k.a. Unicows). It is a GREAT little package that MS did that thunks all the Unicode calls down to ANSI calls on 9x. We use it in our product.
Tim Smith
I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?
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Hello
I was playing around with ATL and find that when we have a function that takes a string as in or out parameters we always use BSTR*. Why don't we use just BSTR? Is it for the obvious pass by pointer reasons?
For example :-
interface INishFirst : IDispatch
{
[id(1), helpstring("method GetString")] HRESULT GetString([in] BSTR* pbstrInString, [out,retval] BSTR* pbstrOutString);
};
Could I have used BSTR there, somehow?
Nish
My most recent CP article :-
A newbie's elementary guide to spawning processes
www.busterboy.org
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Hi Nish,
I think that if you forget the fact that BSTR is really a pointer, then you'll see the answer. If instead of BSTR you were using longs, for example, to pass an [out] parameter, it would be no good having [out, retval] long lResult, as lResult would be copied from the caller and placed on the stack. When the function exits, the caller's lResult would have the same value as it did before the call.
So, in the above example, I wouldn't bother passing in BSTR * for the [in] parameter, but you need to have BSTR * for the [out] parameter so that the caller gets the updated value when the COM method exits.
Sorry, that reads as quite confusing. Hope it helps, though.
------------------------
Derek Waters
derek@lj-oz.com
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