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    <!ENTITY % scons SYSTEM "../scons.mod">
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<chapter id="chap-preface"
         xmlns="http://www.scons.org/dbxsd/v1.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">
<title>Preface</title>

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  <para>

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

  </para>

  <section>
  <title>&SCons; Principles</title>

    <para>

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

    </para>

    <variablelist>

      <varlistentry>
      <term>Correctness</term>

      <listitem>
      <para>

      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.

      </para>
      </listitem>
      </varlistentry>

      <varlistentry>
      <term>Performance</term>

      <listitem>
      <para>

      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.

      </para>
      </listitem>
      </varlistentry>

      <varlistentry>
      <term>Convenience</term>

      <listitem>
      <para>

      &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.

      </para>
      </listitem>
      </varlistentry>

    </variablelist>

    <para>

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

    </para>

  </section>

  <section>
  <title>Acknowledgements</title>

    <para>

    &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:

    </para>

    <para>

    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.

    </para>

    <para>

    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.

    </para>

    <para>

    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).

    </para>

    <para>

    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.

    </para>

  </section>

</chapter>
