I would like to create 2 DLLs. The first DLL will export a handful of Random Number
Generators. The second DLL will allow a client to use the RNG.

I'm having problems with getting the sematics correct in the RNG DLL, so that the
second DLL can take an interface to the 'base class' DLL as an argument.

Here's what I want:
Base Class: PRNG (and interface IPRNG)
Derived: X917C, BBS, LCG, Sequence (and interface IX917C, etc)

In the second DLL, I would like a method such as:
SetRNG( IPRNG* newRNG );

Does anyone have sample code posted? I have not been able to get past a clean compile
on the RNG DLL. I think the problem is with my philosophy - and hence my
implementation. Pure virtuals in the PRNG ATL class cause COM errors. The ATL PRNG
base class in the first DLL compiles OK (but does nothing). When I try to derive from
it (for example, a simple Sequence), a lot of things break. This is after commenting
out a lot of the derived ATL code.

I've looked through a few of my books (Curland's VB book, Box's essential COM), but
neither really talk about - or I have not found a discussion of it. Google has not
lead me to anything useful either (but I probably have not found the proper key words
at this point).

Thanks in advance,
Jeff

If you are trying to use one COM object to expose externally an interface
that is implemented by an internally instantiated COM object, then the
technique for doing this is called "aggregation". That's the key word to
look for when searching MSDN, or any good COM book. However, I just don't
think you need it in the circumstances you describe.

HTH

Brian

There's nothing inherently wrong with what you're doing.  As long as
you cross all the t's and dot all the i's, it looks to me like it
should work.  The only thing that I see that looks like it might not
be right is providing an implementation for PRNG - it looks to me
like that should probably just be an interface that's implemented
by the separate generator coclasses.

--
Craig Powers
MVP - Visual C++

| >
| > I would like to create 2 DLLs. The first DLL will export a handful of Random
Number
| > Generators. The second DLL will allow a client to use the RNG.
| >
| > I'm having problems with getting the sematics correct in the RNG DLL, so that the
| > second DLL can take an interface to the 'base class' DLL as an argument.
| >
| > Here's what I want:
| > Base Class: PRNG (and interface IPRNG)
| > Derived: X917C, BBS, LCG, Sequence (and interface IX917C, etc)
| >
| > In the second DLL, I would like a method such as:
| > SetRNG( IPRNG* newRNG );
| >
| > Does anyone have sample code posted? I have not been able to get past a clean
compile
| > on the RNG DLL. I think the problem is with my philosophy - and hence my
| > implementation. Pure virtuals in the PRNG ATL class cause COM errors. The ATL PRNG
| > base class in the first DLL compiles OK (but does nothing). When I try to derive
from
| > it (for example, a simple Sequence), a lot of things break. This is after
commenting
| > out a lot of the derived ATL code.
| >
| > I've looked through a few of my books (Curland's VB book, Box's essential COM),
but
| > neither really talk about - or I have not found a discussion of it. Google has not
| > lead me to anything useful either (but I probably have not found the proper key
words
| > at this point).
|
| It sounds like these might help:
| http://www.mvps.org/vcfaq/com/7.htm
| http://www.mvps.org/vcfaq/com/8.htm
|
| There's nothing inherently wrong with what you're doing.  As long as
| you cross all the t's and dot all the i's, it looks to me like it
| should work.  The only thing that I see that looks like it might not
| be right is providing an implementation for PRNG - it looks to me
| like that should probably just be an interface that's implemented
| by the separate generator coclasses.
|
| --
| Craig Powers
| MVP - Visual C++

Hi Craig,

Its good to hear from you again (its actually good to hear from anyone who knows more
than I do).

I'm using aggregation as Brian pointed out. I'm using a IPRNG coclass as you
suggested.
The implementation feels like beating a square peg into a round hole.  I can't get a 1
to 1 correspondence of VC++ to COM ATL. Its very awkward.

I'm sorry to give so many details. I know I don't want to read a lot of noise. But in
this context, I think it makes a lot of sense (its a good example) - as does everyone
else!

Jeff