building extensions for Windows Python

Discussion in 'Python' started by JW, Oct 13, 2006.

  1. JW

    JW Guest

    I have a lousy little Python extension, generated with the generous help
    of Pyrex. In Linux, things are simple. I compile the extension, link it
    against some C stuff, and *poof*! everything works.

    My employer wants me to create a Windows version of my extension that
    works with the vanilla Python 2.5 from python.org.

    My employment contract states that I won't be required to run Windows, and
    I desperately want to honor that clause. Ideally, I'd somehow MinGw cross
    compile like I do with C/C++ and *poof*!, out would pop a file I could
    hand out to someone who wanted to "import <my_lousy_extension>".

    In Windows, things aren't so simple. I'm immediately bedazzled by a vast,
    unfamiliar nomenclature: "VC6", "VC7.1", "msvcrt", "msvcr71", "msvcr80",
    "VS2005", "VS2007", "MSVC2003", "MSVC2005", "Express Edition", ".NET SDK",
    etc.

    The python.org "recommended compiler" is apparently no longer
    available, but someone posted a link to an obscure Microsoft webpage
    artifact where it could still be obtained. Running it under WINE is less
    than ideal, but I decided to try and make it work. However, when I tried
    installing the compiler, it failed because my "Internet Explorer [was] out
    of date." I'm not sure how IE comes into the picture, but I'm just a
    programmer, after all.

    I am further confused by the python.org docs on using MinGw to build
    extensions: "These instructions only apply if you're using a version of
    Python prior to 2.4.1 with a MinGW prior to 3.0.0", but further on:
    "pcexports python25.dll >python25.def" seems to contradict that. It
    really makes no difference. The referenced webpage where the "pcexports"
    tool is found seems defunct.

    My main problem is that I don't really grasp the big picture. Can someone
    give me an overview of the requirements to build extensions for Windows
    Python, circa 2.5? Or, can I tell my employer she'll just have to
    hire/contract a Windows expert to do the mud wrestling?

    Jim Wilson
    Gainesville, FL
     
    JW, Oct 13, 2006
    #1
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  2. JW

    Guest

    JW wrote:
    >
    > My main problem is that I don't really grasp the big picture. Can someone
    > give me an overview of the requirements to build extensions for Windows
    > Python, circa 2.5? Or, can I tell my employer she'll just have to
    > hire/contract a Windows expert to do the mud wrestling?
    >
    > Jim Wilson
    > Gainesville, FL


    To build an extension that runs on a generic python 2.5 you need a
    Windows OS (suprise!) and VS.NET 2003. Some people may have had some
    success with MinGW32 (on windows) but it's not going to work
    'out-of-the-box'.

    If your code is straightforward crossplatform C, you could setup a
    distutils configuration script and pass it off to someone else to build
    the windows binaries, but chances are some debugging will have to be
    done.
     
    , Oct 13, 2006
    #2
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  3. On Fri, 2006-10-13 at 11:39 -0400, JW wrote:
    > I have a lousy little Python extension, generated with the generous help
    > of Pyrex. In Linux, things are simple. I compile the extension, link it
    > against some C stuff, and *poof*! everything works.
    >
    > My employer wants me to create a Windows version of my extension that
    > works with the vanilla Python 2.5 from python.org.
    >
    > My employment contract states that I won't be required to run Windows, and
    > I desperately want to honor that clause. Ideally, I'd somehow MinGw cross
    > compile like I do with C/C++ and *poof*!, out would pop a file I could
    > hand out to someone who wanted to "import <my_lousy_extension>".


    I took a very simple pyrex file that compiled and worked fine on linux
    and built it for windows using my mingw cross compiler.

    First I borrowed a complete windows python installation and stuck it on
    my linux drive (in my case in /usr/i386-pc-mingw32/Python2.4.

    Then I just did:

    $ pyrex test.pyx

    $ i386-pc-mingw32-gcc -o test.dll test.c -I/usr/i386-pc-
    mingw32/include/python2.4 -mwindows -shared -lpython24 -L/usr/i386-pc-
    mingw32/Python2.4/lib

    Since there were no special windows libraries used, there were no code
    changes required at all. So look into the mingw cross compiler.
    Usually you have to build it yourself. see
    http://www.torriefamily.org/~torriem/cross for more information. The
    information on the windows target is in the second half of the document.
    This document used the OS X as the build host, but the same steps work
    on linux. I prefer to use /usr/local or /usr as my prefix (ending up
    with /usr/local/bin/i386-pc-mingw32-gcc etc)

    Michael


    >
    > In Windows, things aren't so simple. I'm immediately bedazzled by a vast,
    > unfamiliar nomenclature: "VC6", "VC7.1", "msvcrt", "msvcr71", "msvcr80",
    > "VS2005", "VS2007", "MSVC2003", "MSVC2005", "Express Edition", ".NET SDK",
    > etc.
    >
    > The python.org "recommended compiler" is apparently no longer
    > available, but someone posted a link to an obscure Microsoft webpage
    > artifact where it could still be obtained. Running it under WINE is less
    > than ideal, but I decided to try and make it work. However, when I tried
    > installing the compiler, it failed because my "Internet Explorer [was] out
    > of date." I'm not sure how IE comes into the picture, but I'm just a
    > programmer, after all.
    >
    > I am further confused by the python.org docs on using MinGw to build
    > extensions: "These instructions only apply if you're using a version of
    > Python prior to 2.4.1 with a MinGW prior to 3.0.0", but further on:
    > "pcexports python25.dll >python25.def" seems to contradict that. It
    > really makes no difference. The referenced webpage where the "pcexports"
    > tool is found seems defunct.
    >
    > My main problem is that I don't really grasp the big picture. Can someone
    > give me an overview of the requirements to build extensions for Windows
    > Python, circa 2.5? Or, can I tell my employer she'll just have to
    > hire/contract a Windows expert to do the mud wrestling?
    >
    > Jim Wilson
    > Gainesville, FL
     
    Michael L Torrie, Oct 14, 2006
    #3
  4. JW <> wrote:
    > I have a lousy little Python extension, generated with the generous help
    > of Pyrex. In Linux, things are simple. I compile the extension, link it
    > against some C stuff, and *poof*! everything works.


    ;-)

    > My employer wants me to create a Windows version of my extension that
    > works with the vanilla Python 2.5 from python.org.
    >
    > My employment contract states that I won't be required to run Windows, and
    > I desperately want to honor that clause. Ideally, I'd somehow MinGw cross
    > compile like I do with C/C++ and *poof*!, out would pop a file I could
    > hand out to someone who wanted to "import <my_lousy_extension>".


    You can do that no trouble - we do. We use mingw on linux to compile
    stuff for windows all the time. (We use the mingw package under
    debian)

    We build extensions using mingw but linked to the link library of the
    official python2.4 build. The extensions then run with the standard
    python.org install.

    Here are some (slightly dated) instructions which you'll need to adapt
    to your setup

    /misc/windows is a smb mounted windows machine

    # Linking with the distributed python
    #
    # http://bonsai.ims.u-tokyo.ac.jp/~mdehoon/software/python/cygwin.html
    #
    # On a windows machine
    # install the latest windows python (2.4.3.msi) from www.python.org
    # Copy the header files into the mingw installation
    cp -av /misc/windows/Python24/include /usr/i586-mingw32msvc/include/python2.4
    # Download pexports from here
    # http://www.emmestech.com/software/cygwin/pexports-0.43/download_pexports.html
    # unpack pexports.exe
    unzip pexports-0.43.zip
    # Fetch python dll from the windows machine
    cp -av /misc/windows/WINNT/system32/python24.dll .
    # Extract the exported symbols
    wine pexports python24.dll > python24.def
    # Create the link library
    /usr/i586-mingw32msvc/bin/dlltool --dllname python24.dll --def python24.def --output-lib libpython2.4.a
    # Move the files into the correct place
    mv -i python24.dll python24.def libpython2.4.a /usr/i586-mingw32msvc/lib/

    After that lot you can build python extensions with mingw under linux,
    using -lpython2.4 which will run under windows.

    --
    Nick Craig-Wood <> -- http://www.craig-wood.com/nick
     
    Nick Craig-Wood, Oct 14, 2006
    #4
  5. <> wrote:
    > To build an extension that runs on a generic python 2.5 you need a
    > Windows OS (suprise!) and VS.NET 2003. Some people may have had some
    > success with MinGW32 (on windows) but it's not going to work
    > 'out-of-the-box'.


    Neither of those statements are true. It is fairly easy to build
    python extensions using mingw hosted on linux which work with the
    standard python.org install - see my other post in this thread.

    --
    Nick Craig-Wood <> -- http://www.craig-wood.com/nick
     
    Nick Craig-Wood, Oct 14, 2006
    #5
  6. JW

    JW Guest

    Thanks to Michael and Nick, I can now cross-compile my Pyrex extensions
    for bog-standard Python 2.5. As I stumbled around in the dark trying to
    bump into a solution, I was bolstered by the belief that at least two
    other people had found the light at the end of the tunnel.

    I had been using a crufty old prebuilt MinGW that linked to MSVCRT.DLL but
    didn't include support for the newer VC runtime DLLs. I had to build the
    current version which adds support for MVCR71 (used by Python 2.5) and
    MSVCR80 (used by Microsoft's current ".NET" offering).

    (Note: The build script proffered by mingw.org fails really cryptically if
    you don't have the scanner tool, "flex", installed. But that's another
    story. After some hand-to-hand combat, I had a working MinGW, nee GCC
    3.4.2.)

    Microsoft advises that it's very bad mojo to mix calls to MSVCRT.DLL and
    MSVCR71.DLL in one application, but http://tinyurl.com/ydndnn (or a page
    it references) advises how to avert such a disaster with a simple change
    to MinGW's "spec" file (which I never knew existed).

    The upshot is that I can now use Linux to cross-build my extension for
    Windows, and my preliminary testing (under WINE -- See the original post.
    I must adhere to my employment contract!) seems to show that it works.

    Had I not known someone else claimed success, I would have thrown up my
    hands in frustration.

    Jim Wilson
    Gainesville, FL
     
    JW, Oct 17, 2006
    #6
  7. JW enlightened us with:
    > Thanks to Michael and Nick, I can now cross-compile my Pyrex
    > extensions for bog-standard Python 2.5 [...] I can now use Linux to
    > cross-build my extension for Windows, and my preliminary testing
    > (under WINE -- See the original post. I must adhere to my
    > employment contract!) seems to show that it works.


    Congratulations!

    Sybren
    --
    Sybren Stüvel
    Stüvel IT - http://www.stuvel.eu/
     
    Sybren Stuvel, Oct 17, 2006
    #7
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