Re: CComQIPtr Release

"Igor Tandetnik" <>
Fri, 14 Dec 2007 07:50:54 -0500
<> wrote in message

how i can release CComQIPtr? i mean i want to release this
CComQIPtr for
reuse .this is a member variable.
in certain situation i have to maintain this variable, some times
has to be changed.

You can simply assign a new pointer to your CComQIPtr variable - either
a raw pointer, or another CComPtr or CComQIPtr. It will call Release on
the old pointer it used to hold, and call AddRef on the new pointer.

To release the old pointer without assigning a new one, call
ptr.Release() (note - _not_ ptr->Release() ).

one more doubt any problem CComQIPtr in different thread?because
it says created in different thread,so cannot use.i call CoInitialzeEx
as multithread paramete.

CComQIPtr is not thread-safe, in the sense that you shouldn't modify it
(e.g. you assign a new value) from two threads simultaneously. If you
do, it may leak references.

However, calling methods on the underlying interface through CComQIPtr
instance doesn't modify CComQIPtr itself, so you can safely do it from
multiple threads (as far as CComQIPtr is concerned: the underlying
object must also support it, of course).

The error you seem to be getting has nothing to do with CComQIPtr.
Somehow, you are violating COM rules and passing an interface pointer
(which happens to refer to a proxy) between apartments without proper

You say you use CoInitializeEx to initialize MTA. Are you doing it both
on the thread that created the object, and the other thread that is now
calling its methods? The error suggests you don't.
With best wishes,
    Igor Tandetnik

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