Re: [dbus-cplusplus-devel] dbus-c++ project on sourceforge created

[P. D. <sh...@gm...>]

On Mon, Aug 18, 2008 at 10:25 PM, Andreas Volz <li...@br...> wrote:
> Am Sun, 17 Aug 2008 15:34:49 +0200 schrieb P. Durante:
>
>> On Sun, Aug 17, 2008 at 11:21 AM, Christopher Lang
>> <chr...@ac...> wrote:
>> >
>> > Paolo,
>> >
>> > a question on your code:
>> >
>> > what is that "private" stuff all about? For example in class
>> > "Connection" you are using this:
>> >
>> > class DXXAPI Connection
>> > ...
>> > 59      struct Private;
>> > 60
>> > 61      typedef std::list<Private*> PrivatePList;
>> > 62
>> > 63      Connection( Private* );
>> >
>> > Could you provide a little bit of rationale about this? It somehow
>> > confuses me. Is this simply a "private" dbus connection for example
>> > "app to app" connection? Or is this some (to me unknown) technique
>> > to produce c++ quasi private members in the "public" section?
>> >
>> > many thanks
>> >
>> > Chris
>> >
>> >
>>
>> it's not a private connection, it's the "private data" of that
>> particular class, objects and messages have private data too
>>
>> it's the typical pimpl pattern
>>
>> http://en.wikipedia.org/wiki/Pimpl
>>
>> and it serves two purposes:
>>
>> -copying semantics-
>> DBus::Connection objects (and any object implementing the same idiom)
>> can be copied and all copies will refer to the same, internal, libdbus
>> connection, reference counting is greatly simplified (look at the copy
>> constructor in connection.cpp)
>>
>> -isolation-
>> the public interface of the library (that is, the files under
>> include/) does not depend on libdbus, <dbus/dbus.h> is ONLY EVER
>> included from implementation files (under src/)
>
>
> Thanks for your explanations. I never used that design pattern. But it
> sounds interesting. I'll implement some samples the next days to get
> deeper into this design principle.
>
> As I understood it we could maybe solve that pthread runtime problem
> with the Pimpl design. In eventloop.h is this:
>
> class DXXAPI DefaultMutex
> {
> public:
>
>        DefaultMutex();
>
>        ~DefaultMutex();
>
>        void lock();
>
>        void unlock();
>
> private:
>
> #if defined HAVE_PTHREAD_H
>
>        pthread_mutex_t _mutex;
>
> #elif defined HAVE_WIN32
>
> //TODO: use a critical section
>
> #endif
> };
>
> This was the reason for the private config header. Because if you
> compile dbus-c++ with HAVE_PTHREAD_H and then the app without you'll
> get a silent crash. Wouldn't a Pimpl implementation help here to avoid
> the private config header?
>

yes but in this case it really isn't worth it, I used to want a native
windows but since pthreads already works on windows I just made it a
requirement on the last commit

of course this removes the shameful bug reported earlier today

> regards
> Andreas
>

regards