Linking C++ and Ada

Linking C++ and Ada

[Howard A. Free]

  I've got a question that I'm hoping some of you Ada and C++
  guru's can help me with.

  I'm a grad student at SMU in Software Engineering and I'm
  doing a research project for a company. They want to know how
  to have C++ and Ada code "talk" to each other. Basically they
  want a list of possible solutions and the pro's and con's of
  each.

  I've started by looking at the Ada FAQ and in the Ada Clearing
  House as well as done a WWW search (using various search engines)
  but I haven't come up with much yet.

  Any clues, personal ancedotes (sp?), hits or suggestions on where
  to find some info would be greatly appreciated.

  Howard Free
  hafree@seas.smu.edu

  (Hopefully I've done this correctly. I've not sent many messages
  from a UN*X box. I'd forgotten just how oh-so-friendly they can be.)

Re: Linking C++ and Ada

[Gilles Demailly]

Hi Howard,

check the GNAT examples included in the distribution, there is an example
about calling some C++ code.

--Gilles

Re: Linking C++ and Ada

[Scott Moody, 773-8600]

>check the GNAT examples included in the distribution, there is an example
>about calling some C++ code.

This brings up a question. GNAT has a few pragmas for linking
to C++ that are not part of the Ada standard. I haven't even
seen them until looking at the ex6 example. Should I start using
these non-standard pragmas? It would definitely help my corba interface...

eg.

pragma CPP_Class (Entity => A);
pragma CPP_Vtable (Entity => A, Vtable_Ptr => Vptr, Entry_Count => 2);
pragma CPP_Constructor (Entity => Constructor);

Re: Linking C++ and Ada

[Samuel Tardieu]

>>>>> "Scott" == Scott Moody, 773-8600 <scott@hakuin.boeing.com> writes:

Scott> This brings up a question. GNAT has a few pragmas for linking
Scott> to C++ that are not part of the Ada standard. I haven't even
Scott> seen them until looking at the ex6 example. Should I start
Scott> using these non-standard pragmas? It would definitely help my
Scott> corba interface...

C++ compilers each have their own way of mangling function names to
support overloading. The interface between Ada and C++ implies that
the Ada compiler knows how the C++ compiler changes the function
names. Moreover, there is actually no standard way of implementing
dispatch tables in C++, so this is one more piece of information that
the Ada compiler must know.

Since GNAT and g++ use the same back-end to generate the machine code,
GNAT should do a pretty good job in interfacing with C++. I cannot
imagine how another compiler vendor which does not provide its own C++
compiler could implement this in a better way.

But of course, if you want to stay truly portable, you should
definitively *NOT* use these pragmas and forgive the idea of mixing
C++ and Ada classes :)

  Sam

PS/ as an example, here are the linker names defined by CC and g++ (on
    a Solaris machine) for the following C++ file:

    t.C
    ===
    #include <string.h>
    int f(int x){return x;}
    int f(char *x){return strlen(x);}
    int f(char x){return x;}

    CC
    ==
    __0FBfi
    __0FBfPc
    __0FBfc

    g++
    ===
    f__Fi
    f__FPc
    f__Fc
--
"La cervelle des petits enfants, ca doit avoir comme un petit gout de noisette"
                                                       Charles Baudelaire

Re: Linking C++ and Ada

[Nasser Abbasi]

In article <4gh0sg$j4r@giant.seas.smu.edu>, hafree@seas.smu.edu (Howard A. Free) says:

>  (Hopefully I've done this correctly. I've not sent many messages
>  from a UN*X box. I'd forgotten just how oh-so-friendly they can be.)
>
Look into getting Eudora email system, from Qualcomm Inc. A very 
easy and user firendly email system designed for open systems. 
Runs on many platforms. 

As for your original question, Are you asking about Ada95 or Ada83?

Nasser

Re: Linking C++ and Ada

[Simon Johnston]

> In article <4gh0sg$j4r@giant.seas.smu.edu>, hafree@seas.smu.edu (Howard A.
> Free) says:
>
> >  (Hopefully I've done this correctly. I've not sent many messages
> >  from a UN*X box. I'd forgotten just how oh-so-friendly they can be.)
> >
> Look into getting Eudora email system, from Qualcomm Inc. A very
> easy and user firendly email system designed for open systems.
> Runs on many platforms.

Or Pegasus (DOS, Mac and Windows) which is great and has a nice filtering
system which allows me to seperate all these mailing lists from my incoming
mail.

> As for your original question, Are you asking about Ada95 or Ada83?
>
> Nasser
>
>

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