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

From:

"Alexander Nickolov" <agnickolov@mvps.org>

Newsgroups:

microsoft.public.vc.atl

Date:

Wed, 4 Oct 2006 14:10:25 -0700

Message-ID:

<#wp4Dm$5GHA.4592@TK2MSFTNGP04.phx.gbl>

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
pointers:

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

dispinterface DBlah {
interface IBlah;
}

--
=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================

"Xudong" <chenxudongsg@gmail.com> wrote in message
news:1159924649.383426.214340@e3g2000cwe.googlegroups.com...

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

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
email: agnickolov@mvps.org
MVP VC FAQ: http://www.mvps.org/vcfaq
=====================================

"Igor Tandetnik" <itandetnik@mvps.org> wrote in message
news:%23WEdhKx5GHA.940@TK2MSFTNGP03.phx.gbl...

Alexander Nickolov <agnickolov@mvps.org> 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
to
type info, but only to VARTYPE constants.
--
With best wishes,
Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
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
overhead. -- RFC 1925