3 Getting started on Windows

This chapter describes SWIG usage on Microsoft Windows. Installing SWIG and running the examples is covered as well as building the SWIG executable. Usage within the Unix like environments MinGW and Cygwin is also detailed.

3.1 Installation on Windows

SWIG does not come with the usual Windows type installation program, however it is quite easy to get started. The main steps are:

3.1.1 Windows Executable

The swigwin distribution contains the SWIG Windows executable, swig.exe, which will run on 32 bit versions of Windows, ie Windows 95 and later. If you want to build your own swig.exe have a look at Building swig.exe on Windows.

3.2 SWIG Windows Examples

Using Microsoft Visual C++ is the most common approach to compiling and linking SWIG's output. The Examples directory has a few Visual C++ project files (.dsp files). These were produced by Visual C++ 6. Newer versions of Visual Studio should be able to open and convert these project files. Each C# example comes with a Visual Studio 2005 solution and associated project files instead of Visual C++ 6 project files. The project files have been set up to execute SWIG in a custom build rule for the SWIG interface (.i) file. Alternatively run the examples using Cygwin.

More information on each of the examples is available with the examples distributed with SWIG (Examples/index.html).

3.2.1 Instructions for using the Examples with Visual Studio

Ensure the SWIG executable is as supplied in the SWIG root directory in order for the examples to work. Most languages require some environment variables to be set before running Visual C++. Note that Visual C++ must be re-started to pick up any changes in environment variables. Open up an example .dsp file, Visual C++ will create a workspace for you (.dsw file). Ensure the Release build is selected then do a Rebuild All from the Build menu. The required environment variables are displayed with their current values.

The list of required environment variables for each module language is also listed below. They are usually set from the Control Panel and System properties, but this depends on which flavour of Windows you are running. If you don't want to use environment variables then change all occurrences of the environment variables in the .dsp files with hard coded values. If you are interested in how the project files are set up there is explanatory information in some of the language module's documentation. C#

The C# examples do not require any environment variables to be set as a C# project file is included. Just open up the .sln solution file in Visual Studio .NET 2003 or later, select Release Build, and do a Rebuild All from the Build menu. The accompanying C# and C++ project files are automatically used by the solution file. Java

JAVA_INCLUDE : Set this to the directory containing jni.h
JAVA_BIN : Set this to the bin directory containing javac.exe

Example using JDK1.3:
JAVA_INCLUDE: D:\jdk1.3\include
JAVA_BIN: D:\jdk1.3\bin Perl

PERL5_INCLUDE : Set this to the directory containing perl.h
PERL5_LIB : Set this to the Perl library including path for linking

Example using nsPerl 5.004_04:

PERL5_INCLUDE: D:\nsPerl5.004_04\lib\CORE
PERL5_LIB: D:\nsPerl5.004_04\lib\CORE\perl.lib Python

PYTHON_INCLUDE : Set this to the directory that contains Python.h
PYTHON_LIB : Set this to the python library including path for linking

Example using Python 2.1.1:
PYTHON_INCLUDE: D:\python21\include
PYTHON_LIB: D:\python21\libs\python21.lib TCL

TCL_INCLUDE : Set this to the directory containing tcl.h
TCL_LIB : Set this to the TCL library including path for linking

Example using ActiveTcl
TCL_INCLUDE: D:\tcl\include
TCL_LIB: D:\tcl\lib\tcl83.lib R

R_INCLUDE : Set this to the directory containing R.h
R_LIB : Set this to the R library (Rdll.lib) including path for linking. The library needs to be built as described in the R README.packages file (the pexports.exe approach is the easiest).

Example using R 2.5.1:
R_INCLUDE: C:\Program Files\R\R-2.5.1\include
R_LIB: C:\Program Files\R\R-2.5.1\bin\Rdll.lib Ruby

RUBY_INCLUDE : Set this to the directory containing ruby.h
RUBY_LIB : Set this to the ruby library including path for linking

Example using Ruby 1.6.4:
RUBY_INCLUDE: D:\ruby\lib\ruby\1.6\i586-mswin32
RUBY_LIB: D:\ruby\lib\mswin32-ruby16.lib

3.2.2 Instructions for using the Examples with other compilers

If you do not have access to Visual C++ you will have to set up project files / Makefiles for your chosen compiler. There is a section in each of the language modules detailing what needs setting up using Visual C++ which may be of some guidance. Alternatively you may want to use Cygwin as described in the following section.

3.3 SWIG on Cygwin and MinGW

SWIG can also be compiled and run using Cygwin or MinGW which provides a Unix like front end to Windows and comes free with gcc, an ANSI C/C++ compiler. However, this is not a recommended approach as the prebuilt executable is supplied.

3.3.1 Building swig.exe on Windows

If you want to replicate the build of swig.exe that comes with the download, follow the MinGW instructions below. This is not necessary to use the supplied swig.exe. This information is provided for those that want to modify the SWIG source code in a Windows environment. Normally this is not needed, so most people will want to ignore this section. Building swig.exe using MinGW and MSYS

The short abbreviated instructions follow...

The step by step instructions to download and install MinGW and MSYS, then download and build the latest version of SWIG from Github follow... Note that the instructions for obtaining SWIG from Github are also online at SWIG Bleeding Edge.

Pitfall note: Execute the steps in the order shown and don't use spaces in path names. In fact it is best to use the default installation directories.

  1. Download the following packages from the MinGW download page or MinGW SourceForge download page. Note that at the time of writing, the majority of these are in the Current release list and some are in the Snapshot or Previous release list.
  2. Install MinGW-3.1.0-1.exe (C:\MinGW is default location.)
  3. Install MSYS-1.0.11-2004.04.30-1.exe. Make sure you install it on the same windows drive letter as MinGW (C:\msys\1.0 is default). In the post install script,
  4. Install msysDTK-1.0.1.exe to the same folder that you installed MSYS (C:\msys\1.0 is default).
  5. Copy the following to the MSYS install folder (C:\msys\1.0 is default):
  6. Start the MSYS command prompt and execute:
    cd /
    tar -jxf msys-automake-1.8.2.tar.bz2
    tar -jxf msys-autoconf-2.59.tar.bz2
    tar -zxf bison-2.0-MSYS.tar.gz
  7. The very latest development version of SWIG is available from SWIG on Github and can be downloaded as a zip file or if you have Git installed, via Git. Either download the latest Zip file snapshot and unzip and rename the top level folder to /usr/src/swig. Otherwise if using Git, type in the following:
    mkdir /usr/src
    cd /usr/src
    git clone https://github.com/swig/swig.git
    Pitfall note: If you want to place SWIG in a different folder to the proposed /usr/src/swig, do not use MSYS emulated windows drive letters, because the autotools will fail miserably on those.
  8. The PCRE third party library needs to be built next. Download the latest PCRE source tarball, such as pcre-8.10.tar.bz2, from PCRE and place in the /usr/src/swig directory. Build PCRE as a static library using the Tools/pcre-build.sh script as follows:
    cd /usr/src/swig
  9. You are now ready to build SWIG. Execute the following commands to build swig.exe:
    cd /usr/src/swig
    make Building swig.exe using Cygwin

Note that SWIG can also be built using Cygwin. However, SWIG will then require the Cygwin DLL when executing. Follow the Unix instructions in the README file in the SWIG root directory. Note that the Cygwin environment will also allow one to regenerate the autotool generated files which are supplied with the release distribution. These files are generated using the autogen.sh script and will only need regenerating in circumstances such as changing the build system. Building swig.exe alternatives

If you don't want to install Cygwin or MinGW, use a different compiler to build SWIG. For example, all the source code files can be added to a Visual C++ project file in order to build swig.exe from the Visual C++ IDE.

3.3.2 Running the examples on Windows using Cygwin

The examples and test-suite work as successfully on Cygwin as on any other Unix operating system. The modules which are known to work are Python, Tcl, Perl, Ruby, Java and C#. Follow the Unix instructions in the README file in the SWIG root directory to build the examples.

3.4 Microsoft extensions and other Windows quirks

A common problem when using SWIG on Windows are the Microsoft function calling conventions which are not in the C++ standard. SWIG parses ISO C/C++ so cannot deal with proprietary conventions such as __declspec(dllimport), __stdcall etc. There is a Windows interface file, windows.i, to deal with these calling conventions though. The file also contains typemaps for handling commonly used Windows specific types such as __int64, BOOL, DWORD etc. Include it like you would any other interface file, for example:

%include <windows.i>

__declspec(dllexport) ULONG __stdcall foo(DWORD, __int32);

Note that if you follow Microsoft's recommendation of wrapping the __declspec calls in a preprocessor definition, you will need to make sure that the definition is included by SWIG as well, by either defining it manually or via a header. For example, if you have specified the preprocessor definition in a header named export_lib.h and include other headers which depend on it, you should use the %include directive to include the definition explicitly. For example, if you had a header file, bar.h, which depended on export_lib.h, your SWIG definition file might look like:

// bar.i
%module bar
%include <windows.i>
%include "export_lib.h"
%include "bar.h"

where export_lib.h may contain:

// export_lib.h
#define BAR_API __declspec(dllexport)

and bar.h may look like:

// bar.h
#include "export_lib.h"
BAR_API void bar_function(int, double);

Using the preprocessor to remove BAR_API is a popular simpler solution:

// bar.i
%module bar
#define BAR_API
%include "bar.h"