On Thu, Apr 14, 2005 at 02:24:36PM -0400 Scott Lanning wrote: > On Mon, 11 Apr 2005, Tassilo von Parseval wrote: > >On Mon, Apr 11, 2005 at 08:34:56PM +0100 Nick Ing-Simmons wrote: > >>We could do with updating (and making easier to find) the various > >>tips and tricks of C++/xs. > > > >Which would imply that there is actually an amount of C++/XS tricks > >available in a variety of places. The only two I know of is perlxs.pod > >whose information on that matter are fairly puny, and - of course - > >existing XS modules written in C++ on the CPAN. > > What would be some (good) examples of XS modules using C++?
Good question. I could have sworn that MP3::Id3lib was a good example but now looking at it again, it's hardly C++-ish. An extension definitely written in XS/C++ (with all bells and whistles) is Wx. But this is already so huge and complex, that it's hardly useful for a beginner. > Using http://search.cpan.org and > > cpan> i /c\\+\\+/ > > didn't find anything. I also have an rsync of CPAN which could > be trawled through by gunzipping every distribution and grepping > Makefile.PL for c++, but I didn't try that yet... I very much assume that there wont be so many distributions around. For some reason, C++ isn't nearly as popular as plain C when it comes to XS. Maybe it's because most useful libraries are in fact written in C. For demonstration purpose, I uploaded the little and cursory XS wrapper around <vector> to http://www-users.rwth-aachen.de/Tassilo.Parseval/Vector-0.01.tar.gz and everybody is free to have a look at it. It mainly demonstrates how to use '::' in method names to avoid some typing. Also, it does some overloading in XS, although this is not C++ specific. > Searching on http://perlmonks.org showed a couple relevant threads. > http://perlmonks.org/index.pl?node_id=197028 > ->http://www.johnkeiser.com/perl-xs-c++.html > ->http://cpan.org/authors/id/DMR/ > http://perlmonks.org/index.pl?node_id=225498 > ->http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-12/msg00807.html > > > For the most part, it's pretty straightforward, > but for example how do you deal with passing values > into methods by reference? The ampersand (&) has a special > meaning for XSUB arguments. And return values with references, > since that seems to not work in typemaps (might've been my > mistake, though). I don't know anything about the special meaning of ampersands in XSUB arguments. Is that mentioned somewhere in the docs? Other than that, C++ references are probably best avoided. It severely collides with perl's garbage-collecting when you use C++'s default memory allocator and then pass references to this object around. So the only safe way is to use 'new' and pass the pointer instead of the reference. C++ wont mind. Tassilo -- use bigint; $n=71423350343770280161397026330337371139054411854220053437565440; $m=-8,;;$_=$n&(0xff)<<$m,,$_>>=$m,,print+chr,,while(($m+=8)<=200);
