Re: Rational Apex Ada - Pragma interface with C++

["John Smith" <someone@microsoft.com>]

It doesn't seem to like that idea.  It's complaining about the C++ obect
file.


"Jeffrey Creem" <jeff@thecreems.com> wrote in message
news:Z3Jq9.48415$oq6.12550@sccrnsc01...
> Look for the view switch "NON_ADA_LINKAGE:"
> Add the .o files from the c compile to this switch.
> "John Smith" <someone@microsoft.com> wrote in message
> news:H3zuq4.G8y@news.boeing.com...
> > Hello Matthew,
> >
> > I just tried your suggestion, but I don't quite know how to link it.  I
> > compiled the C++ module that contains the externs with the CC compiler
> from
> > Sun OS and compiled the C code that interfaces with the C++ module with
> cc.
> > Now my problem is how do I link both together?  I've generated two
object
> > files, but then I'm stuck.  Help please.
> >
> > John
> >
> >
> > "Matthew Heaney" <mheaney@on2.com> wrote in message
> > news:uqbtbu6rtkk7b@corp.supernews.com...
> > >
> > > "John Smith" <someone@microsoft.com> wrote in message
> > > news:H3s05H.LMt@news.boeing.com...
> > > > Does anyone know how to use pragma interface for interfacing C++
> > functions
> > > > to an Ada program.  I know how to do it with C, but can't seem to
get
> it
> > > to
> > > > work with C++.
> > >
> > > Interfacing with C++ requires care, especially if you have static
> > variables
> > > the require elaboration-time initialization.
> > >
> > > When a C++ program loads, all the statics get initialized.  There will
> be
> > > some code inserted by the compiler to go this, just prior to call the
> C++
> > > main.
> > >
> > > The same is true of an Ada program.
> > >
> > > In general, a C++ program will need a C++ main, and an Ada program
will
> > need
> > > an Ada main.
> > >
> > > If you don't have any statics, you may OK.
> > >
> > > There's no official function you can call from an Ada program to
perform
> > the
> > > C++ initialization -- you'll have to check your compiler docs.
> > >
> > > There are official functions to perform Ada initialization -- there
are
> > two
> > > linker symbols called "adainit" and "adafinal".  If you have a C++
main,
> > and
> > > you're calling code written in Ada, then you'll need to call these.
> > >
> > > In any event, there's no pragma to interface with C++ directly.  I
know
> > GNAT
> > > has compiler-specific pragmas to do this.
> > >
> > > However, I wouldn't bother.  Just create a C wrapper, and link to
those.
> > > For example, if you have a C++ class you want to use from Ada, like
> this:
> > >
> > > class C
> > > {
> > > public:
> > >    void f();
> > > //...
> > > };
> > >
> > > Assuming you don't mind manipulating a pointer, you can do this:
> > >
> > > extern "C" C* makeC()
> > > {
> > >    return new C;
> > > }
> > >
> > > extern "C" void freeC(C* p)
> > > {
> > >    delete p;
> > > }
> > >
> > > extern "C" void c_f(C* p)
> > > {
> > >    p->f();
> > > }
> > >
> > > On the Ada side, create a set of bindings for each of the external
> > functions
> > > above, e.g.
> > >
> > > function Make_C return System.Address;
> > > pragma Interface (C, Make_C);
> > >
> > > procedure Free_C (Object : System.Address);
> > > pragma Interface (C, Free_C);
> > >
> > > procedure C_F (Object : System.Address);
> > > pragma Interface (C, C_F);
> > >
> > > You could add more type safety than I've shown above, e.g.
> > >
> > > package C_Types is
> > >
> > >    type C_Type (<>) is limited private;
> > >
> > >    type C_Access is access all C_Type;
> > >    pragma Convention (C, C_Access);
> > >
> > >    function New_C return C_Access;
> > >
> > >    procedure Free (C : in out C_Access);
> > >
> > >    procedure Do_F (C : access C_Type);
> > >
> > > private
> > >
> > >    type C_Type is null record;
> > >
> > >    function Make_C return C_Access;
> > >    pragma Interface (C, Make_C);
> > >
> > >   --etc
> > > end C_Types;
> > >
> > >
> > >
> > >
> >
> >
>
>