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<H1><a name="Preface">1 Preface</a></H1>
<!-- INDEX -->
<div class="sectiontoc">
<li><a href="#Preface_nn2">Introduction</a>
<li><a href="#Preface_nn4">SWIG Versions</a>
<li><a href="#Preface_license">SWIG License</a>
<li><a href="#Preface_nn5">SWIG resources</a>
<li><a href="#Preface_nn6">Prerequisites</a>
<li><a href="#Preface_nn7">Organization of this manual</a>
<li><a href="#Preface_nn8">How to avoid reading the manual</a>
<li><a href="#Preface_nn9">Backwards compatibility</a>
<li><a href="#Preface_release_notes">Release notes</a>
<li><a href="#Preface_nn10">Credits</a>
<li><a href="#Preface_nn11">Bug reports</a>
<li><a href="#Preface_installation">Installation</a>
<li><a href="#Preface_windows_installation">Windows installation</a>
<li><a href="#Preface_unix_installation">Unix installation</a>
<li><a href="#Preface_osx_installation">Macintosh OS X installation</a>
<li><a href="#Preface_testing">Testing</a>
<li><a href="#Preface_examples">Examples</a>
<!-- INDEX -->
<H2><a name="Preface_nn2">1.1 Introduction</a></H2>
SWIG (Simplified Wrapper and Interface Generator) is a software development tool for building scripting language
interfaces to C and C++ programs. Originally developed in 1995, SWIG was
first used by scientists in the Theoretical Physics Division at Los Alamos National Laboratory for
building user interfaces to simulation codes running on the Connection
Machine 5 supercomputer. In this environment, scientists needed to
work with huge amounts of simulation data, complex hardware, and a
constantly changing code base. The use of a scripting language
interface provided a simple yet highly flexible foundation for solving these
types of problems. SWIG simplifies development by largely automating
the task of scripting language integration--allowing developers and users
to focus on more important problems.
Although SWIG was originally developed for scientific applications, it
has since evolved into a general purpose tool that is used in a wide
variety of applications--in fact almost anything where C/C++ programming
is involved.
<H2><a name="Preface_nn4">1.2 SWIG Versions</a></H2>
In the late 1990's, the most stable version of SWIG was release
1.1p5. Versions 1.3.x were officially development versions and these were released
over a period of 10 years starting from the year 2000. The final version in the 1.3.x
series was 1.3.40, but in truth the 1.3.x series had been stable for many years.
An official stable version was released along with the decision to make SWIG
license changes and this gave rise to version 2.0.0 in 2010.
Version 3.0.0 was released in 2014 focusing on adding C++11 support and C++ nested classes.
Version 4.0.0 was released in 2019 to add in Doxygen support.
Some target languages were disabled as part of a clean up and others were given a new status of either 'Supported' or 'Experimental'.
<H2><a name="Preface_license">1.3 SWIG License</a></H2>
The LICENSE file shipped with SWIG in the top level directory contains the SWIG license.
For further insight into the license including the license of SWIG's output code, please visit
the SWIG legal page - <a href=""></a>.
The license was clarified in version 2.0.0
so that the code that SWIG generated could be distributed
under license terms of the user's choice/requirements and at the same time the SWIG
source was placed under the GNU General Public License version 3.
<H2><a name="Preface_nn5">1.4 SWIG resources</a></H2>
The official location of SWIG related material is
<div class="shell"><pre>
<a href=""></a>
This site contains the latest version of the software, users guide,
and information regarding bugs, installation problems, and
implementation tricks.
You can also subscribe to the swig-user mailing list by visiting the page
<div class="shell"><pre>
<a href=""></a>
The mailing list often discusses some of the more technical aspects of
SWIG along with information about beta releases and future work.
Git and Subversion access to the latest version of SWIG is also available. More information
about this can be obtained at:
<div class="shell"><pre>
<a href="">SWIG Bleeding Edge</a>
<H2><a name="Preface_nn6">1.5 Prerequisites</a></H2>
This manual assumes that you know how to write C/C++ programs and that you
have at least heard of scripting languages such as
Tcl, Python, and Perl. A detailed knowledge of these scripting
languages is not required although some familiarity won't
hurt. No prior experience with building C extensions to these
languages is required---after all, this is what SWIG does automatically.
However, you should be reasonably familiar with the use of
compilers, linkers, and makefiles since making
scripting language extensions is somewhat more complicated than
writing a normal C program.
Over time SWIG releases have become significantly more capable in
their C++ handling--especially support for advanced features like
namespaces, overloaded operators, and templates. Whenever possible,
this manual tries to cover the technicalities of this interface.
However, this isn't meant to be a tutorial on C++ programming. For many
of the gory details, you will almost certainly want to consult a good C++ reference. If you don't program
in C++, you may just want to skip those parts of the manual.
<H2><a name="Preface_nn7">1.6 Organization of this manual</a></H2>
The first few chapters of this manual describe SWIG in general and
provide an overview of its capabilities. The remaining chapters are
devoted to specific SWIG language modules and are self
contained. Thus, if you are using SWIG to build Python interfaces, you
can probably skip to that chapter and find almost everything you need
to know.
<H2><a name="Preface_nn8">1.7 How to avoid reading the manual</a></H2>
If you hate reading manuals, glance at the "Introduction" which
contains a few simple examples. These
examples contain about 95% of everything you need to know to use
SWIG. After that, simply use the language-specific chapters as a reference.
The SWIG distribution also comes with a large directory of
examples that illustrate different topics.
<H2><a name="Preface_nn9">1.8 Backwards compatibility</a></H2>
If you are a previous user of SWIG, don't expect
SWIG to provide complete backwards compatibility.
Although the developers strive to the utmost to keep backwards compatibility,
this isn't always possible as the
primary goal over time is to make SWIG
better---a process that would simply be impossible if the developers
are constantly bogged down with backwards compatibility issues.
Potential incompatibilities are clearly marked in the detailed
<a href="#Preface_release_notes">release notes</a>.
If you need to work with different versions of SWIG and backwards
compatibility is an issue, you can use the SWIG_VERSION preprocessor
symbol which holds the version of SWIG being executed.
SWIG_VERSION is a hexadecimal integer such as 0x010311 (corresponding to SWIG-1.3.11).
This can be used in an interface file to define different typemaps, take
advantage of different features etc:
<div class="code"><pre>
#if SWIG_VERSION &gt;= 0x010311
/* Use some fancy new feature */
Note: The version symbol is not defined in the generated SWIG
wrapper file. The SWIG preprocessor has defined SWIG_VERSION since SWIG-1.3.11.
<H2><a name="Preface_release_notes">1.9 Release notes</a></H2>
The CHANGES.current, CHANGES and RELEASENOTES files shipped with SWIG in the top level directory
contain, respectively, detailed release notes for the current version,
detailed release notes for previous releases and summary release notes from SWIG-1.3.22 onwards.
<H2><a name="Preface_nn10">1.10 Credits</a></H2>
SWIG is an unfunded project that would not be possible without the
contributions of many people working in their spare time.
If you have benefitted from using SWIG, please consider
<a href="">Donating to SWIG</a> to keep development going.
There have been a large varied number of people
who have made contributions at all levels over time. Contributors
are mentioned either in the COPYRIGHT file or CHANGES files shipped with SWIG or in submitted bugs.
<H2><a name="Preface_nn11">1.11 Bug reports</a></H2>
Although every attempt has been made to make SWIG bug-free, we are also trying
to make feature improvements that may introduce bugs.
To report a bug, either send mail to the SWIG developer
list at the <a href="">swig-devel mailing list</a> or report a bug
at the <a href="">SWIG bug tracker</a>. In your report, be as specific as
possible, including (if applicable), error messages, tracebacks (if a
core dump occurred), corresponding portions of the SWIG interface file
used, and any important pieces of the SWIG generated wrapper code. We
can only fix bugs if we know about them.
<H2><a name="Preface_installation">1.12 Installation</a></H2>
<H3><a name="Preface_windows_installation">1.12.1 Windows installation</a></H3>
Please see the dedicated <a href="Windows.html#Windows">Windows chapter</a> for instructions on installing
SWIG on Windows and running the examples. The Windows distribution is
called swigwin and includes a prebuilt SWIG executable, swig.exe, included in
the top level directory. Otherwise it is exactly the same as
the main SWIG distribution. There is no need to download anything else.
<H3><a name="Preface_unix_installation">1.12.2 Unix installation</a></H3>
These installation instructions are for using the distributed tarball,
for example, <tt>swig-3.0.8.tar.gz</tt>.
If you wish to build and install from source on Github, extra steps are required.
Please see the <a href="">Bleeding Edge</a> page on the SWIG website.
You must use <a href="">GNU make</a> to build and install SWIG.
<a href="">PCRE2</a>
needs to be installed on your system to build SWIG, in particular
pcre2-config must be available. If you have PCRE2 headers and libraries but not
pcre2-config itself or, alternatively, wish to override the compiler or linker
flags returned by pcre2-config, you may set PCRE2_LIBS and PCRE2_CFLAGS variables
to be used instead. And if you don't have PCRE2 at all, the configure script
will provide instructions for obtaining it.
To build and install SWIG, simply type the following:
<div class="shell"><pre>
$ ./configure
$ make
$ make install
By default SWIG installs itself in /usr/local. If you need to install SWIG in
a different location or in your home directory, use the <tt>--prefix</tt> option
to <tt>./configure</tt>. For example:
<div class="shell"><pre>
$ ./configure --prefix=/home/yourname/projects
$ make
$ make install
Note: the directory given to <tt>--prefix</tt> must be an absolute pathname. Do <b>not</b> use
the ~ shell-escape to refer to your home directory. SWIG won't work properly
if you do this.
The INSTALL file shipped in the top level directory details more about using configure. Also try
<div class="shell"><pre>
$ ./configure --help.
The configure script will attempt to locate various packages on your machine
including Tcl, Perl5, Python and all the other target languages that SWIG
supports. Don't panic if you get 'not found' messages -- SWIG does not need these
packages to compile or run. The configure script is actually looking for
these packages so that you can try out the SWIG examples contained
in the 'Examples' directory without having to hack Makefiles.
Note that the <tt>--without-xxx</tt> options, where xxx is a target language, have
minimal effect. All they do is reduce the amount of testing done with
'make check'. The SWIG executable and library files installed cannot currently
be configured with a subset of target languages.
SWIG used to include a set of runtime libraries for some languages for working
with multiple modules. These are no longer built during the installation stage.
However, users can build them just like any wrapper module as described in
the <a href="Modules.html#Modules">Modules chapter</a>.
The CHANGES file shipped with SWIG in the top level directory
also lists some examples which build the runtime library.
If you checked the code out via Git, you will have to run <tt>./</tt>
before <tt>./configure</tt>. In addition, a full build of SWIG requires
a number of packages to be installed. Full instructions at
<a href="">SWIG bleeding edge</a>.
<H3><a name="Preface_osx_installation">1.12.3 Macintosh OS X installation</a></H3>
SWIG is known to work on various flavors of OS X. Follow the Unix installation
instructions above. However, as of this writing, there is still great deal of
inconsistency with how shared libraries are handled by various scripting languages
on OS X.
Users of OS X should be aware that Darwin handles shared libraries and linking in
a radically different way than most Unix systems. In order to test SWIG and run
the examples, SWIG configures itself to use flat namespaces and to allow undefined
symbols (<tt>-flat_namespace -undefined suppress</tt>). This mostly closely follows the Unix
model and makes it more likely that the SWIG examples will work with whatever
installation of software you might have. However, this is generally not the recommended
technique for building larger extension modules. Instead, you should utilize
Darwin's two-level namespaces. Some details about this can be found here
<a href="">Understanding Two-Level Namespaces</a>.
Needless to say, you might have to experiment a bit to get things working at first.
<H3><a name="Preface_testing">1.12.4 Testing</a></H3>
If you want to test SWIG after building it, a check can be performed on Unix operating systems.
Type the following:
<div class="shell"><pre>
$ make -k check
This step can be performed either before or after installation.
The check requires at least one of the target languages to be
installed. If it fails, it may mean that you have an uninstalled
language module or that the file 'Examples/Makefile' has been
incorrectly configured. It may also fail due to compiler issues such
as a broken C++ compiler. Even if the check fails, there is a
pretty good chance SWIG still works correctly --- you will just have to
mess around with one of the examples and some makefiles to get it to work.
Some tests may also fail due to missing dependency packages, eg PCRE
or Boost, but this will require careful analysis of the configure output
done during configuration.
The test suite executed by the check is designed to stress-test
many parts of the implementation including obscure corner cases. If some
of these tests fail or generate warning messages, there is no reason for
alarm --- the test may be related to some new SWIG feature or a difficult bug
that we're trying to resolve. Chances are that SWIG will work just fine
for you. Note that if you have more than one CPU/core, then you can use
parallel make to speed up the check as it does take quite some time to run,
for example:
<div class="shell"><pre>
$ make -j2 -k check
Also, SWIG's support for C++ is sufficiently advanced that certain
tests may fail on older C++ compilers (for instance if your compiler
does not support member templates). These errors are harmless if you
don't intend to use these features in your own programs.
Note: The test-suite currently contains over 600 tests. If you
have many different target languages installed and a slow machine, it
might take more than an hour to run the test-suite.
<H3><a name="Preface_examples">1.12.5 Examples</a></H3>
The Examples directory contains a variety of examples of using SWIG
and it has some browsable documentation. Simply point your browser to
the file "Example/index.html".
The Examples directory also includes Visual C++ project 6 (.dsp) files for
building some of the examples on Windows. Later versions of Visual Studio
will convert these old style project files into a current solution file.