Re: Design question - interfacing with lots of different hardware architectures

From:

"Daniel T." <daniel_t@earthlink.net>

Newsgroups:

comp.lang.c++

Date:

Sat, 02 Aug 2008 21:30:51 -0400

Message-ID:

<daniel_t-0EA97D.21305102082008@earthlink.vsrv-sjc.supernews.net>

"Angus" <nospam@gmail.com> wrote:

My program works with different types of telephone system. Their interfaces
are all different.

But, of course, I don't want to have to write a different program for each
system. There is a LOT of code in the existing program which interfaces
with just one telephone system. I can re-use a lot of that. But I want a
flexible interface to the hardware.

My thinking is I would need to use some sort of polymorphic interface class.
Is this idea along the right lines:

Probably not. I would only do the above is I had to change hardware at
runtime and I have a feeling that isn't the case.

One option that I consider better is a variation of the handle-body or
pimpl idiom.

Make your "Telephone.h" like this:

class Telephone {
   struct Impl;
   Impl* pimpl;
public:
   void connect();
   void disconnect();
   // &c.
};

Now define the "Telephone::Impl struct inside the Telephone.cpp file and
implement the functions as appropriate.

Now here is the cool bit. Write Multiple Telephone.cpp files
(ThisTelephone.cpp, ThatTelephone.cpp, SoOnTelephone.cpp) with each one
dedicated to a specific hardware.

Now when you compile for a particular hardware, use the appropriate cpp
file. QED.

Then my next problem is that the telephone system sends event information.
some of it is unsolicited (ie no request generated the event). How would I
model that?

Sounds like an Observer pattern would be appropriate.