Re: [paragui-users] the dll low down

[Andrew Ford]

Can you fix this by placing static variables in their
own anonymous namespace:

namespace {
    static pgWhatever lookImHidden;
}

Stroustrup's book mentions something about it...

Andrew.

--- Alexander Pipelka <address@hidden> wrote:
> Hmm,...
> 
> There's one thing that came to my mind after your
> last email:
> Are you linking your dll's statically to ParaGUI (I
> think i read this in
> your CWproject readme) ?
> 
> It won't work this way.
> 
> Why ?
> 
> Because ParaGUI hold a whole bunch of static
> variables (the globall app
> object, widgetlists, messagemaps,...).
> If you link it statically every dll will be a
> seperate ParaGUI instance.
> 
> Solution ?
> Create a ParaGUI dll and link it with your main app
> and your "plugin"
> dlls.
> 
> Alex
> 
> Am Die, 2002-06-04 um 17.29 schrieb Keith Swyer:
> > ok, i'll geive you some nice details.....
> > 
> > - i am using a base class that all the dlls are
> based from
> > 
> > class Area{
> > public:
> >     virtual void FillArea(void *data, void *data2)
> = 0;
> > private:
> >     friend class dll_object_ref<Area>;
> >     virtual void destroy()=0;
> > };
> > 
> > - in the dlls i create i use the Area base class,
> then call a macro
> > FACTORY_ENTRY(newclass, name)
> > which then calls this....  allowing us to have a
> clean way to access the
> > names without the c++ mangled crap.
> > (externc is a macro for extern "c" and dllfunc is
> just the export )
> > #define FACTORYFUNC( base , the_class , prefix ,
> classid ) \
> >   EXTERNC DLLFUNC base* DLLCALL prefix##classid(
> void )    \
> >     { return new the_class; }
> > 
> > - these are the DLL support classes: dll_sentinel,
> dll_object_ref, and
> > dll_object_ptr.
> > Class dll_sentinel is responsible for ensuring
> that the DLL is resident
> > during the sentinel's lifetime. It keeps track of
> both the DLL name and the
> > handle to that DLL. The first time a dll_sentinel
> is created, it asks the OS
> > to load the DLL, and the OS sets the DLL's
> reference count to one. Every
> > time another dll_sentinel loads the same DLL, the
> OS increments that DLL's
> > reference count. When each dll_sentinel is
> destroyed, it asks the OS to
> > close the DLL. The OS actually just decrements the
> DLL's reference count,
> > and unloads the DLL only when that count reaches
> zero.
> > dll_object_ref contains a dll_sentinel, a pointer
> to an object residing in
> > the DLL, and a reference count. When a
> dll_object_ref is constructed, it
> > finds the appropriate function in the DLL and uses
> it to initialize its
> > pointer. When the dll_object_ref is destroyed, it
> deletes the object pointed
> > to.
> > 
> > dll_object_ptr is similar to std::auto_ptr, except
> that its ownership
> > semantics are slightly different. Copying one
> dll_object_ptr to another does
> > not cause one of them to become invalidated or to
> lose ownership of the
> > underlying object. Because dll_object_ptr takes
> advantage of
> > dll_object_ref's reference counting scheme, the
> underlying object gets
> > destroyed only when all of its dll_object_ptrs are
> destroyed.
> > 
> > Now that i hopefully have you all confused  :)  i
> don't have a way that each
> > dll instanciates themselves automatically yet, but
> right now my factory
> > template allows you to instantiate by referring to
> the name of the
> > class.....anyway, this all works fine and i can
> call _object->FillArea
> > fine, but inside of that function in the dll i
> cannot use any of the paragui
> > functions.
> > 
> > 
> > 
> > well, i hope this isn't too much to wrap your
> heads around as i know i'm
> > getting a litte off paragui specific (but i am
> planing to add this somehow
> > to pg) any help would be great. I know this isn't
> probably the best way to
> > do what i'm doing, but i've had to figure this all
> out by looking around the
> > net, and i'm only new to using and making dlls... 
>  :)
> > 
> > 
> > 
> > --Keith
> > 
> > 
> > 
> > _______________________________________________
> > paragui-users mailing list
> > address@hidden
> >
>
http://mail.freesoftware.fsf.org/mailman/listinfo/paragui-users
> 
> 
> 
> 
> _______________________________________________
> paragui-users mailing list
> address@hidden
>
http://mail.freesoftware.fsf.org/mailman/listinfo/paragui-users


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