From: Tobias Peters <tpeters@...>
Date: 2002-04-10T10:31:14+09:00
Subject: Re: C++ extensions, garbage collection, Ruby and SWIG

On 8 Apr 2002, Phil Tomson wrote:
> "Be sure to understand ruby's memory management before attempting to 
> design your classes. Since you want to write a "C++ extension to Ruby", 
> you should defer all memory management to the ruby interpreter."
>  - Tobias Peters
> 
> That actually sounds like good advice, however the library I want to 
> 'swig' already has 'automated garbage collection' as a feature.  Will this 
> cause trouble?  Are there ways to work around the problems that might 
> be caused by this?

Hi Phil,

then you should seek to understand both memory management implementations
and find a way to to have them working together in the same process.
Sorry, I cannot give you more advice, since I don't know (and don't want
to learn) how the buddy lib manages its memory. The easiest libraries to
wrap are those with explicit reference counting, then you can just
reference a c++ object when you wrap it in a ruby object and dereference
it from free. Similar are C++ libraries that encapsulate their worker
objects through smart pointers, which is just a way to hide reference
counting from the application programmer in constructors and destructors.

But with every other kind of library you are on your own. You have to
examine which objects are managed by the library and which are supposed to
be managed by the user, and when the ownership changes and such.

Good luck,
Tobias