Metaprogramming and
Free Availability of Sources
Two Challenges for Computing Today^*

Abstract:

We introduce metaprogramming in a completely informal way, and sketch out a theory of it. We explain why it is a major stake for computing today, by considering the processes underlying software development. We show, from the same perspective, how metaprogramming is related to another challenge of computing, the free availability of the sources of software, and how these two phenomena naturally complement each other.

1  Introduction

In the primitive settings of early computing, the size of machines was so small that a one man's mind could fully embrace the whole of a program's activity down to the least details. Now, the human faculties haven't evolved since, whereas the capacities of computers have increased at a sustained geometric progression. To benefit from the technological advance, ever more abstract conceptual tools and programming languages had to be developed and used.

But however great the progress made by programmers as individuals, the level of complexity has been long exceeded beyond which no one can conceive the entirety of a program that would take full advantage of existing computers. It is therefore of utmost importance to develop methods of exchange, cooperation, accumulation, construction, so as to elaborate complex programs; such is the field of software engineering [].

Now, central to any process of building software is manipulation of the source code of programs. To enhance these processes, to ease the task of the programmer, is to relieve the programmer from all repetitive and conceptually redundant operations, so that he may focus on the essence of programming, that is, on the problems that have never been solved yet. This means manipulation of code must be automated as much as possible, by having machines handle reliably all the inferior tasks that do not pose theoretical problems anymore. And to automate programming is by definition metaprogramming.

Thus, metaprogramming, the art of programming programs that read, transform, or write other programs, appears naturally in the chain of software development, where it plays an essential role, be it “only” under the form of compilers, interpreters, debuggers. However, metaprogramming is almost never consciously integrated in the processes of development, and gaining awareness of its role is precisely the first step towards progress in this domain.

Now, even if we would like to focus on the technical task, which is sufficiently hard in itself, consisting in the exploration of automation methods for the software development process, it is impossible for us to ignore the precondition necessary to the use of any such method as well as to any cooperative or incremental work: the availability of sources.

This availability is less than ever a technical problem, thanks to the advent of digital telecommunications; but it is more than ever a political problem, at a time when the near-totality of information on the planet is under control of publishing monopolies organized in powerful lobbies. The Free Software movement fights for the free availability of source code, nay, information in general; it opposes the artificial tollgates that the legal priviledges of “intellectual property” are.