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Re: Problem concerning accessing external library in IDL6.0 [message #47746]

Thu, 02 March 2006 09:55

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

yingjie, Peng wrote:

> Thanks for your kind reply. I think the problem is that the library
> which I used (DirectX.Capture.dll) is COM object, but it is not an
> ActiveX library. It is a .NET library. In .NET framework, you do not
> need to (or simply you can't) register the .NET library. This
> function is used to simplify coding within the .NET framework, such as
> C#. However, for us, the IDL user, we can't use ActiveX control to
> access this kind of library any more since we can't get the CLSID.

Are you *sure* you can't get the CLSID? Again, I am not a .NET guy, but
I see a ".NET Category" in my COM/OLE browser. I can then look for
something that I might be able to find docs or guess a method... I see:

"System.Random"

I use the COM/OLE browser to get the CLSID and then create the IDL COM
object:

test=obj_new('IDLcomIDispatch$CLSID$4E77EC8F_51D8_386C_85FE_ 7DC931B7A8E7')

I then try to guess a method or two, and fail. Then I go to the VS .net
docs, find the .net random class, see that the method to get a random
number is "next" and voila!

IDL> print, test->next()
1957853535
IDL> print, test->nextdouble()
0.80895216
IDL> print,test->tostring()
System.Random
IDL> print,test->gethashcode()
54267293

So I think you should at least *try* to find the CLSID using the COM/OLE
browser. I mean it will only take a few minutes and you may save
yourself a lot of time.

If you do find the CLSID, you still may not be "out of the woods" as we
say. I have had mixed success with IDL's COM interface. Simple things
tend to work, but more complex methods can run into problems. For
example, the nextbytes method of our aforementioned system.random object
seemed very straightforward. It fills a byte array with random bytes.
So you would think it would be as easy as:

IDL> a=bytarr(5)
IDL> print, test->nextbytes(a)
IDLCOMIDISPATCH$CLSID$4E77EC8F_51D8_386C_85FE_7DC931B7A8E7:: NEXTBYTES:
Unable to call method NEXTBYTES.
The parameter is incorrect.

I tried numerous variations with no success. I'm sure there is a
reason, and maybe some way to get it to work, but my point is that it
isn't always smooth sailing on the IDL COM seas.

So in the end you may end up writing a DLM anyways. It isn't as hard as
it may seem, especially if you buy Ronn Kling's book "Calling C from
IDL". You can order it from his website www.kilvarock.com.

Good luck!

-Rick

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[Message index]

		Re: Problem concerning accessing external library in IDL6.0 By: Rick Towler on Thu, 02 March 2006 09:55
		Re: Problem concerning accessing external library in IDL6.0 By: Haje Korth on Thu, 02 March 2006 05:32
		Re: Problem concerning accessing external library in IDL6.0 By: ronn on Thu, 02 March 2006 02:35
		Re: Problem concerning accessing external library in IDL6.0 By: yingjie, Peng on Wed, 01 March 2006 14:54
		Re: Problem concerning accessing external library in IDL6.0 By: yingjie, Peng on Wed, 01 March 2006 14:52
		Re: Problem concerning accessing external library in IDL6.0 By: ronn on Tue, 28 February 2006 13:41
		Re: Problem concerning accessing external library in IDL6.0 By: Rick Towler on Tue, 28 February 2006 10:51
		Re: Problem concerning accessing external library in IDL6.0 By: ronn on Mon, 06 March 2006 05:23

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