# Preface

This document assumes that you already know how &SCons; and that you want to learn how to work on the code.

## &SCons; Principles

There are a few overriding principles we try to live up to in designing and implementing &SCons;:

Correctness

  First and foremost, by default, &SCons; guarantees a correct build even if it means sacrificing performance a little. We strive to guarantee the build is correct regardless of how the software being built is structured, how it may have been written, or how unusual the tools are that build it.

Performance

  Given that the build is correct, we try to make &SCons; build software as quickly as possible. In particular, wherever we may have needed to slow down the default &SCons; behavior to guarantee a correct build, we also try to make it easy to speed up &SCons; through optimization options that let you trade off guaranteed correctness in all end cases for a speedier build in the usual cases.

Convenience

  &SCons; tries to do as much for you out of the box as reasonable, including detecting the right tools on your system and using them correctly to build the software.

In a nutshell, we try hard to make &SCons; just "do the right thing" and build software correctly, with a minimum of hassles.

## Acknowledgements

&SCons; would not exist without a lot of help from a lot of people, many of whom may not even be aware that they helped or served as inspiration. So in no particular order, and at the risk of leaving out someone:

First and foremost, &SCons; owes a tremendous debt to Bob Sidebotham, the original author of the classic Perl-based &Cons; tool which Bob first released to the world back around 1996. Bob's work on Cons classic provided the underlying architecture and model of specifying a build configuration using a real scripting language. My real-world experience working on Cons informed many of the design decisions in SCons, including the improved parallel build support, making Builder objects easily definable by users, and separating the build engine from the wrapping interface.

Greg Wilson was instrumental in getting &SCons; started as a real project when he initiated the Software Carpentry design competition in February 2000. Without that nudge, marrying the advantages of the Cons classic architecture with the readability of Python might have just stayed no more than a nice idea.

Thanks to Peter Miller for his splendid change management system, &Aegis;, which has provided the &SCons; project with a robust development methodology from day one, and which showed me how you could integrate incremental regression tests into a practical development cycle (years before eXtreme Programming arrived on the scene).

And last, thanks to Guido van Rossum for his elegant scripting language, which is the basis not only for the &SCons; implementation, but for the interface itself.