Re: C++ draft

[Yao Qi <qiyaoltc@gmail.com>]

On Tue, Jun 28, 2011 at 5:08 AM, Tom Tromey <tromey@redhat.com> wrote:
> I've been working on another proposal to move gdb to C++.  I'd
> appreciate help with it.  Here is what I have so far.
>
> Do you find it reasonably convincing?  If not, why not?  What can be
> improved?  Are there other good initial targets for conversion?  Are
> there lurking problems of which I am unaware?
>

I don't have special preference over C or C++.

> My proposal is:
>
> 1. Modify GDB so it can be compiled with -Wc++-compat.
>   This would be the first patch series.  There is already an archer
>   branch for this.
>
> 2. Then, change GDB to compile with a C++ compiler (-Wc++-compat is
>   not complete).  This would be the second patch series.
>
> 3. Require C++.
>
> 4. Change selected modules to use C++ rather than C.
>   I don't think a wholesale change makes sense, but some areas would
>   benefit.
>
>   My first target would be to change the exception handling system to
>   use C++ exception.  This would enable us to begin using RAII in
>   some areas, which would help robustness.
>
>   My concrete plan here is:
>
>   * Use the GCC cleanup-checking plugin I already wrote to detect
>     cleanup-aware functions.
>
>   * Modify these functions, using a script, to add an RAII-using
>     object to manage the local cleanups.  This is important so that
>     we run cleanups at the correct time during stack unwinding.
>
>   * Change throw_exception to use 'throw' and all TRY_EXCEPT
>     instances to try...catch.
>
>   * Finally, convert functions to static RAII usage when appropriate;
>     this will be an ongoing transition.
>
>   I think our second target will be sorting out Python reference
>   counting, so we can avoid the many problems we have had there.
>

Tom,
In your concrete plan, IIUC, your plan is about converting GDB to C++
*partially*, instead of re-write GDB *completely*.  Is that correct?
For example, I don't anything in your plan about converting *-tdep.c
stuff into C++.   Is it in your plan or we plan to leave them as they
are now?

Do we plan to move gdbserver to C++?  I think no, because some
baremental boards have too few memory to hold a C++ application.  So
we are in a state that both C and C++ co-exist in GDB for some time.
I don't think C and C++ co-existance is a problem, or, your plan is
about "make good use of C++ to replace some bad and error-prone stuffs
in GDB, and keep the rest of GDB as it is".  Is it right?

Just want to know clearly what GDB will be after your plan is performed.

-- 
Yao Qi <qiyaoltc AT gmail DOT com>
http://sites.google.com/site/duewayqi/