From: Will Gwaltney <will.gwaltney@...>
Date: 2004-10-07T01:54:48+09:00
Subject: How to determine supported dispinterfaces for WIN32OLE object?

I'm using WIN32OLE_EVENT to set up some event handlers on various DHTML
elements in Internet Explorer, and I'm having a bit of trouble identifying
the right event dispinterfaces to use.  The Microsoft online documentation
is less than helpful; they claim that you can use the HTMLElementEvents2
interface on most all the HTML elements you care about, but I'm getting the
following when I try:

interface not found
    HRESULT error code:0x80004002
      No such interface supported

Here's a code skeleton that outlines what I'm trying to do:

---------------- (snip) -----------------------

require 'win32ole'

ie = WIN32OLE.new('InternetExplorer.Application')

     .
     .
     .
 insert code to display a web page here...
     .
     .
     .

elements =  ie.document.all
elements.each do |element|
     ev = WIN32OLE_EVENT.new(element, 'HTMLElementEvents2')
      .
      .
      .
     assign event handlers here
      .
      .
      .
end

---------------- (snip) -----------------------

And here's the URL for the Microsoft documentation that makes the claims
about the HTMLElementEvents2 interface:
http://msdn.microsoft.com/workshop/browser/mshtml/tutorials/sink.asp

What am I missing?  Do I have to somehow massage the element into a
different object that will handle the HTMLElementEvents2 interface?  Or
should I be using another interface entirely?  (BTW, is there any way in
WIN32OLE to figure out which interfaces an object supports?)

Any help will be much appreciated!

Will Gwaltney
SAS Institute