Orchid XP v8 wrote:
> They have a beta already? Damn, that was fast...

No, the beta is already *expired*. :-)

>> Yes. It's a dynamically-linked library. Says it right there in the 
>> name. :-)
> 
> In other words, it's a shared library. I more or less knew they before. ;-)

Not necessarily shared. Just dynamically linked. It happens that on Windows 
(and Linux, as far as I know) that such libraries are indeed shared. But you 
can have dynmamic linking without sharing and you can have sharing without 
dynamic linking.

> (According to Wikipedia, seems to be GetProcAddress()...)

Yes.

> Sure. But in this case, I'm talking about Microsoft RPC. As in, that 
> service that if it stops running, your entire PC shuts down for some 
> reason... (MS Blaster, anyone?)

It shuts down because huge amounts of the OS are built premised on the 
availability of COM. It doesn't completely shut down, of course, but 
everything *interesting* does.

> According to the documentation, you write an MIDL file, and the compiler 
> generates a header file and two C source code files. 

It generates a TBL file, which your tool then reads to generate whatever 
language-specific bindings you want.

> Because the MIDL compiler generates this code, so technically you don't 
> need to know how it actually works. 

A) No it doesn't. It also generates a TBL file.

B) You'd have to know how it works to interface it to any language not 
written in C.

> I'm reasonably sure NT 4 has DCOM, 

Could be, could be.

>> Exactly. Plus, it's an active object, i.e., what people call an "Actor". 
> 
> ...you mean the object can be doing other stuff by itself before you 
> specifically ask it to do something?

Yes. As I said, "Excel" is a COM object. It's running in a separate process. 
That's why it's not just a DLL.

>> A process running Excel is basically one big COM object, with methods 
>> like "open a spreadsheet" and "return the value of column B row 27." 
>> That's how people do these automation tasks.
> 
> Heh. I had always assumed that such tasks are simply impossible, because 
> I've never come across a programming language that can do them. (Well, 
> except VB. And who the hell understands that?)

*Every* language can do it. I've done it from Tcl (as well as writing COM 
servers). It's trivial from C# and as trivial as anything is in C, and VB, 
and WSH. Like I said, WSH is basically a shell designed to do nothing but 
COM calls.

> But, uh, isn't IDispatch::Invoke *itself* a COM method??
> 
> Seriously, I see CoInitialise() and CoUninitialise() to start/stop the 
> COM library. I see CoGetClassObject() and CoCreateInstanceEx(), but I 
> can't see a CoCallMethod() or similar anywhere.

Hmmm.  Well, ship me the two C files from your MIDL, and I'll tell you what 
the call it. :-)

> Well, maybe I need to sit down and spend some time creating "COM 
> support" for Haskell, and then everything will become trivial. :-P

That's the general idea, yes.

-- 
   Darren New, San Diego CA, USA (PST)
   I ordered stamps from Zazzle that read "Place Stamp Here".

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