From: Simon Strandgaard <0bz63fz3m1qt3001@...>
Date: 2003-04-11T01:05:08+09:00
Subject: Re: embedding ruby with swig

On Thu, 10 Apr 2003 08:33:10 +0000, Steve Hart wrote:

> Thanks for the reply - sorry if I kept you up!

The hardest part of my day is when I have to move myself from
the computer over to my bed (2 meters). I hate sleeping :-)


> I think I've sussed the problem and oh dear, how stupid could I be!
> The problem I had was that even though the mark function gets called
> so does free immediately afterwards. This is because i declare tObj
> once, pass a reference to rb_gc_register_address and then next time
> round the loop just overwrite it. 

I am not sure about the purpose of your code. 
guess: an experiment to see what happens when GC kicks in.
Thats a rather complicated proof of concept you have.

I have done some experiments too, try
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/metaeditor/experiments/cpp_embed_ruby/test/garbage/
maybe I should add it to the tutorial ???



[snip maip.cpp]

variable-declarations = street-respect :-)


I think you have gotton out on a off-track. Both malloc/free and
marking is unnecessary. I know you really want to use rb_gc_mark(), but
you are not in the situation where its necessary to mark your children.
You are using it to mark non-children...mark is not supposed to be used 
in that way. 

 
> I'm a bit doubtful about the malloc - should I do something different
> here?
> It all works though
> I also had to change the mark and free functions in swig to:
 
[snip swig.i]


> I'm also unsure regarding the static_cast. I've seen examples using
> static_cast,dynamic_cast,reinterpret_cast and no cast at all.

http://cpptips.hyperformix.com/cpptips/cast_overview


> I'm still unclear on one issue though. I supply a mark function for
> swig and
> sure enough this gets called now, so why do I have to register the
> object (tObj) on the c++ side?

I think you should see the example that mentioned earlier, this should
hopefully make it a bit more clear for you.

--
Simon Strandgaard