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Thank you for taking the time to read about &SCons;.
&SCons; is a next-generation
software construction tool,
or make tool--that is, a software utility
for building software (or other files)
and keeping built software up-to-date
whenever the underlying input files change.
The most distinctive thing about &SCons;
is that its configuration files are
written in the &Python; programming language.
This is in contrast to most alternative build tools,
which typically invent a new language to
configure the build.
&SCons; still has a learning curve, of course,
because you have to know what functions to call
to set up your build properly,
but the underlying syntax used should be familiar
to anyone who has ever looked at a Python script.
using Python as the configuration file format
for non-programmers to learn
than the cryptic languages of other build tools,
which are usually invented by programmers for other programmers.
This is in no small part due to the
consistency and readability that are built in to Python.
It just so happens that making a real, live
scripting language the basis for the
makes it a snap for more accomplished programmers
to do more complicated things with builds,
&SCons; is a response to a perennial problem:
building software is harder than it should be.
In a nutshell: the old, reliable model of the
venerable and ubiquitous &Make; program
has had a hard time keeping up with
how complicated building software has become.
The fact that &Make; has kept up as well as it has is impressive,
and a testament to how the simplicity.
But anyone who has wrestled with &Automake; and &Autoconf;
to try to guarantee that a bit of software
will build correctly on multiple platforms
can tell you that it takes a lot of work to get right.
There are a few overriding principles
we try to live up to in designing and implementing &SCons:
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.
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.
&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.
&SCons; originated with a design
that was submitted to the Software Carpentry
design competition in 2000.
&SCons; is the direct descendant
of a Perl utility called &Cons;.
&Cons; in turn based some of its ideas on &Jam;,
a build tool from Perforce Systems.
XXX history of SCons
XXX conventions used in this manual
<title>A Caveat About This Guide's Completeness</title>
One word of warning as you read through this Guide:
Like too much Open Source software out there,
the &SCons; documentation isn't always
kept up-to-date with the available features.
In other words,
there's a lot that &SCons; can do that
isn't yet covered in this User's Guide.
(Come to think of it,
that also describes a lot of proprietary software, doesn't it?)
Although this User's Guide isn't as complete as we'd like it to be,
our development process does emphasize
making sure that the &SCons; man page is kept up-to-date
with new features.
So if you're trying to figure out how to do something
that &SCons; supports
but can't find enough (or any) information here,
it would be worth your while to look
at the man page to see if the information is covered there.
And if you do,
maybe you'd even consider contributing
a section to the User's Guide
so the next person looking for
that information won't have to
go through the same thing...?
&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.
The entire &SCons; team have been
absolutely wonderful to work with,
and &SCons; would be nowhere near as useful a
tool without the energy, enthusiasm
and time people have contributed over the past few years.
The "core team"
of Chad Austin, Anthony Roach,
Bill Deegan, Charles Crain, Steve Leblanc, Greg Noel,
Gary Oberbrunner, Greg Spencer and Christoph Wiedemann
have been great about reviewing my (and other) changes
and catching problems before they get in the code base.
Of particular technical note:
Anthony's outstanding and innovative work on the tasking engine
has given &SCons; a vastly superior parallel build model;
Charles has been the master of the crucial Node infrastructure;
Christoph's work on the Configure infrastructure
has added crucial Autoconf-like functionality;
and Greg has provided excellent support
for Microsoft Visual Studio.
Special thanks to David Snopek for contributing
his underlying "Autoscons" code that formed
the basis of Christoph's work with the Configure functionality.
David was extremely generous in making
this code available to &SCons;,
given that he initially released it under the GPL
and &SCons; is released under a less-restrictive MIT-style license.
&SCons; has received contributions
from many other people, of course:
Matt Balvin (extending long command-line support on Windows),
Allen Bierbaum (extensions and fixes to Options),
Steve Christensen (help text sorting and function action signature fixes),
Michael Cook (avoiding losing signal bits from executed commands),
Derrick 'dman' Hudson (),
Alex Jacques (work on the Windows scons.bat file),
Stephen Kennedy (performance enhancements),
Lachlan O'Dea (SharedObject() support for masm
and normalized paths for the WhereIs() function),
Damyan Pepper (keeping output like Make),
Jeff Petkau (significant fixes for CacheDir and other areas),
Stefan Reichor (Ghostscript support),
Zed Shaw (Append() and Replace() environment methods),
Terrel Shumway (build and test fixes, as well as the SCons Wiki)
sam th (dynamic checks for utilities).
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.
The best way to contact people involved with SCons,
including the author,
is through the SCons mailing lists.
If you want to ask general questions about how to use &SCons;
send email to &scons-users;.
If you want to contact the &SCons; development community directly,
send email to &scons-devel;.
If you want to receive announcements about &SCons,
join the low-volume &scons-announce; mailing list.