From: Daniel Berger <djberg96@...>
Date: 2007-06-20T00:24:25+09:00
Subject: Re: Problem wrapping the C++ STL



On Jun 19, 1:07 am, Sylvain Joyeux <sylvain.joy...@polytechnique.org>
wrote:
> > g++ -Wall -I. -I/opt/lib/ruby/1.8/i686-darwin8.9.1
> > -I/opt/lib/ruby/1.8/i686-darwin8.9.1 -I.  -fno-common -g -O2 -pipe
> > -fno-common  -c cvector.c
> > cvector.c: In function 'void Init_cvector()':
> > cvector.c:10: error: invalid conversion from 'VALUE (*)(int, VALUE*,
> > VALUE)' to 'VALUE (*)(...)'
> > cvector.c:10: error:   initializing argument 3 of 'void
> > rb_define_method(VALUE, const char*, VALUE (*)(...), int)'
> > make: *** [cvector.o] Error 1
>
> C++ is more pissy than C about type convertions. You have to use the
> RUBY_METHOD_FUNC macro to convert cvector_init into the right type:
>
>   rb_define_method(cVector, "initialize",
>       RUBY_METHOD_FUNC(cvector_init), -1);

Ah, thanks.

> > > Note that you can wrap std::vector directly (no need to go through an
> > > intermediate cvector structure)
>
> > I guess I could store it as an instance variable within the constructor
> > and refer back to it that way. I don't think it's faster, though. Or,
> > did you have something else in mind?
>
> The idea is *not* to use a cvector structure. Since you'll have to provide
> an alloc/free method pair anyway, allocate std::vector in them. Check
> value_set_alloc/value_set_free inhttp://www.laas.fr/~sjoyeux/darcs/utilrb/ext/value_set.cc

Interesting, thank you. For kicks, I tried to compile your source code
on my Solaris 10 box (after installing boost). It built (with some
warnings), but I can't get it to load.

Here's the extconf.rb file I used:

require 'mkmf'
dir_config('set2')

case RUBY_PLATFORM
   when /sunos|solaris/
      CONFIG['CC'] = 'CC'
   when /mswin/i
      CONFIG["COMPILE_C"].sub!(/-Tc/, '-Tp')
   else
      CONFIG['CC'] = 'g++ -Wall'
end

create_makefile('set2')

Here was the result of the build step:

djberge-/export/home/djberge/workspace/set/ext-635>ruby extconf.rb --
with-set2-include=/opt/csw/include
creating Makefile

djberge-/export/home/djberge/workspace/set/ext-636>make
CC -I. -I/usr/local/lib/ruby/1.8/sparc-solaris2.10 -I/usr/local/lib/
ruby/1.8/sparc-solaris2.10 -I. -I/opt/csw/include -KPIC -dalign -fns -
xbuiltin=%all -xlibmil -xtarget=ultra2e -xO5 -xipo -c set.c
"set.c", line 349: Warning (Anachronism): Formal argument 3 of type
extern "C" unsigned long(*)(...) in call to rb_iterate(extern "C"
unsigned long(*)(unsigned long), unsigned long, extern "C" unsigned
long(*)(...), unsigned long) is being passed unsigned long(*)(...).
"set.c", line 369: Warning (Anachronism): Formal argument 2 of type
extern "C" unsigned long(*)(unsigned long) in call to
rb_define_alloc_func(unsigned long, extern "C" unsigned long(*)
(unsigned long)) is being passed unsigned long(*)(unsigned long).
2 Warning(s) detected.
ld -G -o set2.so set.o -L'.' -L'/usr/local/lib' -R'/usr/local/lib' -
L.  -lrt -lpthread -ldl -lcrypt -lm   -lc

Ok, a couple warnings. I proceed to try to "require 'set2'" and I get
this:

djberge-/export/home/djberge/workspace/set/ext-637>ruby test.rb
/export/home/djberge/workspace/set/ext/set2.so: ld.so.1: ruby: fatal:
relocation error: file /export/home/djberge/workspace/set/ext/set2.so:
symbol __1cDstdJbad_allocG__vtbl_: referenced symbol not found - /
export/home/djberge/workspace/set/ext/set2.so (LoadError)
        from /usr/local/lib/ruby/site_ruby/1.8/rubygems/
custom_require.rb:27:in `require'
        from test.rb:2

This was with Ruby 1.8.6-p38 (today's svn checkout of the 1.8.6
branch).

Any ideas?

Dan