For the past seven years, a considerable amount of effort has gone into the development of SWIG and its support for various programming languages. Currently, more than a dozen developers work on the system and there are thousands of users. However, almost all of SWIG's development has been relatively ad-hoc---primarily driven by feature requests from users. As SWIG's original author, coordinating all of this chaos has always been a bit of challenge. In fact, it's been rather difficult to even describe what SWIG "is" and "how it works" without using terms like "magic" and, well, "more magic." Needless to say, this isn't the most academic way to look it ;-).
A little over a year ago, I became interested in the relationship between SWIG and work in the area of type systems. In order to support advanced C++ features like namespaces and templates, a significant amount of very difficult development work focused on the SWIG type system. Moreover, this work resulted in a lot of old SWIG features being folded into type system extensions. Because of this work, I have now come to view SWIG as being mostly driven as an extension of the C++ type system rather than an extension of a C++ parser. This difference is subtle, but it is the only way to really understand how SWIG works at a fundamental level.
To the best of my knowledge, no one working on automatic C/C++ wrapper generators has really approached the wrapping problem from the standpoint of type systems. Instead, everyone seems to focus on the problem of parsing C++, which, although important, is not enough to really understand what is going on.
Starting in the summer of 2003, the NSF will be funding a research project at the University of Chicago to explore the relationship between type-systems and wrapper generation in more detail. A lot of this work will involve SWIG and the semantics of its underlying type system. Moreover, this work will be exploring some exciting new features such as software contracts and improved mixed-language debugging support. We're also going to try and make connections between SWIG and related work in the area of programming languages.
What does this mean for the future of SWIG? Well, my hope is that this work will make the system more capable, more reliable, and more useful than ever. I think everyone will be pleasantly surprised with some of the changes.
As always, I'd like to acknowledge everyone who has contributed to SWIG over the years---thank you for your support!
Cheers,
Dave Beazley
March 23, 2003