Re: can event handler call event source passed as connection point parameter?

"Alexander Nickolov" <>
Wed, 4 Oct 2006 14:10:25 -0700
Yes, you understood right.

Your proposal for a warning is reasonable. There's one other
way to specify a pure dispinterface - by inheriting the
description of a COM interface - where this may also apply
if the original interface included methods accepting interface

interface IBlah : IUnknown {
    HRESULT method([in] IDual*);

dispinterface DBlah {
    interface IBlah;

Alexander Nickolov
Microsoft MVP [VC], MCSD

"Xudong" <> wrote in message

Can I say the conclusion is: only IUnknown/IDispatch can be passed via

dispinterface can only be called via Invoke therefore its methods can
only specify IUnknown/IDispatch interfaces. Then I have a suggestion:
why not let MIDL compiler warn programmers or report errors if other
interfaces are specified?

Now I notice and understand that only IDispatch is given in
DWebBrowserEvents2 :)

Thanks, Alexander and Igor!

Alexander Nickolov wrote:

Correct. The code before that could certainly perform QI,
but apparently it doesn't. It's be an overkill if it did - essentially
replicating the work of DispCallFunc.

I believe a pure dispinterface can only accept IDispatch and
IUnknown pointers by definition, and specifying a derived
interface in IDL instead is only syntactic sugar. After all, the
dispinterface is the implemenation of IDispatch, not the class
methods it calls within, which are implementation-specific.

Alexander Nickolov
Microsoft MVP [VC], MCSD

"Igor Tandetnik" <> wrote in message

Alexander Nickolov <> wrote:

This is a pure dispinterface, so DispInvoke is not involved.

Ah, I see. For some reason I thought IDispEvent[Simple]Impl uses
DispInvoke, but in fact it uses DispCallFunc which does not have access
type info, but only to VARTYPE constants.
With best wishes,
   Igor Tandetnik

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necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
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