Boost logo

Boost :

From: Rene Rivera (grafik.list_at_[hidden])
Date: 2005-12-27 16:13:36

Andrew Schweitzer wrote:
>>Andrew Schweitzer wrote:
>>>5) demuxer_service creates a platform-implementation demuxer_service
> Rene Rivera wrote:
>>Not as far as I know. This is one of the points that some people have
>>contention with. The real relation between demuxer_service and the
>>implementation is closer to a PIMPL idiom, but without the pointer. In
>>other words it's equivalent to:
>> demuxer_service *is-a*
>> detail::win_iocp_demuxer_service
> [snip]
> I think I'm confused. As far as I can tell, there's no inheritance
> relationship between demuxer_service and win_iocp_demuxer_service, but
> as you said, it's a PIMPL relation, or perhaps an RIMPL relation since
> it's a reference not a pointer.

We can consider the reference as just a different kind of pointer in
this case. After all it could just as easily be a pointer and the
forwarding functions would deref the pointer, instead of the compiler
doing the deref for you.

> Is PIMPL considered is-a or has-a?

I've always considered it an is-a. A very special case, but equivalent.

> I think the library design or naming might be a bit confused on this
> point (or quite possibly it's me).

The fact that it's confusing, even when looking at the code, is a point
against the design ;-) OK, I'm rereading the code, instead of relying on

> As far as I can tell two things are true:
> 1) the demuxer ends up with two actual services in its list after it
> is constructed:
> a) demuxer_service
> b) win_iocp_demuxer_service (or the selected
> platform-implemenation of demuxer_service)

OK, AFAICT it only ends up with (b) in the service_registry.

> 2) the demuxer also has a PIMPL relation with demuxer_service,
> and demuxer_service has a PIMPL relation with
> win_iocp_demuxer_service

Yes. I guess the key point here is that there's only 1 (singleton) of
win_iocp_demuxer_service for all demuxer_service instances in the same
basic_demuxer instance? (again AFAICT)

> Are you reading the code differently? I might have gotten lost.

I guess, I'm reading it differently :-)

-- Grafik - Don't Assume Anything
-- Redshift Software, Inc. -
-- rrivera/ - grafik/
-- 102708583/icq - grafikrobot/aim - Grafik/

Boost list run by bdawes at, gregod at, cpdaniel at, john at