DragonFly kernel List (threaded) for 2009-01
Re: C++ in the kernel
On Sun, Jan 04, 2009 at 07:26:15PM +0100, Pieter Dumon wrote:
> It's just political, there's pros and cons for everything.
> Its not because LT says something that it's true.
I agree. I don't worship at that alter, so it was more the content and
relevance for which I was going.
> Some people have demonstrated nice work in C++ (e.g. some L4 variants).
> Whatever language you use, it all comes down to using it properly.
> But if your whole kernel is written in C, better to leave it at that :-)
> The worst thing you can do is mix and match C and C++ I think - that
> would be really crappy.
Again, I completely agree. I have no dog in this fight...other than
the fact that I don't know C++ very well :).
> On Sun, Jan 4, 2009 at 5:25 PM, B. Estrade <email@example.com> wrote:
> > On Sun, Jan 04, 2009 at 05:06:13PM +0100, Michael Neumann wrote:
> >> This question bugs me since a quite long time so I write it down...
> >> FreeBSD had a long thread about pros and cons of using C++
> >> in the kernel here .
> >> I'm undecided whether it would be good to use C++ in the DragonFly kernel.
> >> At first, most importantly, there is the question about the quality of
> >> the C++ compiler (bug-freeness) and the quality of the generated machine
> >> code.
> >> I can't answer this for sure, just did a small test compiling
> >> the same C code with both a C and a C++ compiler. Both produce the same
> >> machine code.. Using C++ classes without all the more advanced stuff
> >> (like exception, RTTI...) shouldn't make too much a difference in the
> >> produced code. So I don't think this will be much of a problem.
> >> Next thing to consider is the possible abuse of C++'s features
> >> (exceptions, RTTI etc.). I don't think this is a problem either,
> >> especially in a small project like DragonFly, as there is only a handful
> >> of developers. The solution to this problem is as simple as just don't
> >> use those features.
> >> Now to the advantages of C++ that IMO would make sense:
> >> * Think about the kobj and the driver architecture. All this comes
> >> for free when using C++. No .m files anymore. Everything in
> >> one language.
> >> * Think about macro-driven datastructures (e.g. rbtree).
> >> They are IMHO quite unreadable and very hackish.
> >> C++ templates on the other hand are a lot cleaner
> >> (they are sometimes ugly as well :).
> >> Of course templates doesn't help when using internal
> >> datastructures like sys/queue.h.
> >> Maybe I spent too much time using OO languages (like Ruby or C++).
> >> What I am missing most in C is the ability to subclass structures,
> >> methods and templates. All this IMHO can improve expressability
> >> and code quality.
> > I can't pretend to know what this implies for DfBSD, I think Linus has
> > addressed this before wrt Linux:
> > http://lwn.net/Articles/249460/
> > I don't know enough C++ to share his opinion, nor do I contribute to
> > any projects, but I think this might be some good background on the
> > matter.
> > Cheers,
> > Brett
> >> Regards,
> >> Michael
> >> http://lists.freebsd.org/pipermail/freebsd-arch/2007-October/006969.html
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