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List:       ms-atl
Subject:    Re: Can connection point event pass a variant and so on?
From:       Jiaxu Li <jli () SFAMIPEC ! COM>
Date:       2000-10-31 17:20:08
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I answered the first question myself.

The Wizard generates code as
void Fire_OnEvent(VARIANT newVal)
{
        ...
        CComVariant *pVar[1];
        pVar[0] = &newVal;
        ...
}

The operator = in CComVariant will use its InternalCopy(...). This causes
the error. I modified the Wizard code to pVar->Copy( &newVal ); then works.

Thanks for reading!

JLi

-----Original Message-----
From: Jiaxu Li [mailto:jli@SFAMIPEC.COM]
Sent: Thursday, October 26, 2000 4:59 PM
To: ATL@DISCUSS.MICROSOFT.COM
Subject: Re: Can connection point event pass a variant and so on?


Sorry for misprints !!

In 1, I meant "I CAN NOT compile ..." instead of "I can compile ...;
In 2, "class CMyClass" should be "struct ItemStruct".

Sorry about that!!

JL

-----Original Message-----
From: Jiaxu Li [mailto:jli@SFAMIPEC.COM]
Sent: Thursday, October 26, 2000 4:41 PM
To: ATL@DISCUSS.MICROSOFT.COM
Subject: Can connection point event pass a variant and so on?


I have two questions as follows.

1. I use ATL connection point to raise some events. One is called
Fire_OnData(). Ideally, I like to pass a variant (containing
multi-dimensional SafeArray) to clients, i.e., Fire_OnData ( VARIANT newVal
);. On client side, clients will implement OnData(.) and play with the
variant.

But, I can compile my ATL COM server code. The error is the variant is
truncated to boolean.

I take an alternative approach for test purpose (other parts).
a) Fire event without parameter, Fire_OnData();.
b) Write another method get_Data(VARIANT newVal) so that clients can get the
data after received the event.
This costs me an extra round trip.

Please let me know if I can pass variant through the event method. ( I have
no problem to pass long and BSTR. ) Thank you in advance!

2. I use STL queue to queue my user defined class CMyClass in the way

#typedef struct {
...
} ItemStruct;

#typedef queue<ItemStruct> MYQUEUE
MYQUEUE myQ;

My code likes
///////////////////////////////
{
        ObjectLock(this);
        while ( !myQ.empty() )
        {
                ItemStruct item;
                item = myQ.front(); // <- the line at which the program
fails.
                // do some things on item
                myQ.pop();
        }
}
///////////////////////////////
After 3.5 hours running and looping 290,000+ times, it fails at the line
"item = myQ.front();". Entering debug mode, I saw myQ.empty() returns 0 and
myQ.front() returns error. This gives me the impression that the queue
contains a garbage item. I'm sure it is not from client. Can anyone tell me
what's wrong? Thank you in advance again!

JLI

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