Re: Connection Point for interfaces

"Igor Tandetnik" <>
Fri, 5 May 2006 07:33:31 -0400
"Andrey" <> wrote in message

You say that interfaces don't have connection point support.
But how are implemented some interfaces in NET Framework to
support events? For example in "System.ComponentModel"
there is an IBindingList interface. And this interface has
"ListChanged" event.

ListChanged is simply a property whose value happens to be a delegate.
In COM terms, you could represent it as a pair of methods taking a
callback interface:

interface IListChangedEventHandler : IUnknown {
    HRESULT OnEvent([in] IUnknown* sender);

interface IBindingList : IUnknown {
    HRESULT Advise([in] IListChangedEventHandler*);
    HRESULT Unadvise([in] IListChangedEventHandler*);

In this sense, an interface can "support" "events", though in COM this
technique is usually referred to as a callback, not an event. The term
"events" usually means those fired via IConne?tionPoint.
With best wishes,
    Igor Tandetnik

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