Re: how to prevent objects from being garbage collected.

meinrad recheis wrote:
> is there a way to prevent objects from being destructed by the ruby 
> garbage collector or at the end of the script, without having to write 
> markfunks for the owner of these objects?

I haven't yet had a chance to study the responses so far, but I wanted 
to let you know that I hit a similar problem, and have implemented a 
slightly ugly but effective solution.

In my case, the C++ objects might be considered to have "shared" 
ownership, where they could legitimately be deleted from the ruby side, 
or by the C++ library that I am wrapping. The C++ side will not ask my 
permission before deleting the objects, so it is important that I be 
able to detect later that it has happened.

Unfortunately, if C++ deletes the object first, then Ruby invokes the 
free_xxx method that was passed at the time the object was created, and 
that method has no protection against re-deleting the already-deleted 
object.

Here's my approach so far. Note that I have only ONE c++ class per 
source code file, which simplifies the map handling:

1. Make sure every class that might have this problem is wrapped with a 
director.
2.  Declare and define a static hash/map variable. Each entry in the map 
will have the C++ object as the key, and the associated Ruby object as 
the value.
3. In the director constructor, add this/self to the map.
4. In the director destructor, remove this/self from the map.
5. In the free_xxx function, only delete the pointer if it is in the map.

This seems to have solved the problem for me.

I am already having to do post-processing of each swigged file for 
several other reasons, so this is just another pesky step for me. 
Eventually, I would like to see some feature like this built into 
SWIG/Ruby (and other language bindings, if it is also a problem there).

Perhaps one of the other replies in this thread has suggested a better 
approach. That would be great.

Kevin
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