Re: Using a static library in a C extension for Python
On Thursday, January 23, 2014 3:22:52 AM UTC+8, lgabiot wrote: Le 22/01/14 18:31, 8 Dihedral a écrit : Check the C source code generated by Pyrex and check cython for what u want, but I did try that out in any mobile phone or flat panel programming. Thanks a lot for your answer. I didn't use Pyrex or other tool, but wrote myself the C python wrapping, using the Python C/API documentation (http://docs.python.org/2/c-api/). I then used the distutils tool (via a setup.py file) to build my extension. While there is several function in my C code, only one needed to be accessed by python. I'll check Cython then, but is there any tweaking of the setup.py file using distutils that will help me compile the extension with the cairo lib embedded into it? There are some design concerns in writing python scripts that might be modified for fast execution speeds in some platforms. Well, reducing basic operation overheads in well factored critical parts does help in getting the desired results faster. -- https://mail.python.org/mailman/listinfo/python-list
Using a static library in a C extension for Python
Hello, working on OS X 10.8.5 Python 2.7 I've written a simple C extension for Python that uses the cairo graphic library. It works well, and I can call it from Python with no problem. The only drawback is that I need to have the cairo library installed on my system (so it seems my extension calls dynamically the cairo library). I believe this because it doesn't work on a system where cairo is not installed. Is it possible to link statically cairo to my extension, so that even if cairo is not installed on a computer, the code will run? I guess I would need to modify the setup.py file using distutils to compile cairo statically into my .so file? Or am I completely wrong? If someone has a hint... thanks! -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
On Wednesday, January 22, 2014 7:01:50 PM UTC+8, lgabiot wrote: Hello, working on OS X 10.8.5 Python 2.7 I've written a simple C extension for Python that uses the cairo graphic library. It works well, and I can call it from Python with no problem. The only drawback is that I need to have the cairo library installed on my system (so it seems my extension calls dynamically the cairo library). I believe this because it doesn't work on a system where cairo is not installed. Is it possible to link statically cairo to my extension, so that even if cairo is not installed on a computer, the code will run? I guess I would need to modify the setup.py file using distutils to compile cairo statically into my .so file? Or am I completely wrong? If someone has a hint... thanks! Check the C source code generated by Pyrex and check cython for what u want, but I did try that out in any mobile phone or flat panel programming. -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
Le 22/01/14 18:31, 8 Dihedral a écrit : Check the C source code generated by Pyrex and check cython for what u want, but I did try that out in any mobile phone or flat panel programming. Thanks a lot for your answer. I didn't use Pyrex or other tool, but wrote myself the C python wrapping, using the Python C/API documentation (http://docs.python.org/2/c-api/). I then used the distutils tool (via a setup.py file) to build my extension. While there is several function in my C code, only one needed to be accessed by python. I'll check Cython then, but is there any tweaking of the setup.py file using distutils that will help me compile the extension with the cairo lib embedded into it? -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
lgabiot wrote: Le 22/01/14 18:31, 8 Dihedral a écrit : Check the C source code generated by Pyrex ... Thanks a lot for your answer. We suspect that 8 Dihedral is actually a bot, so you're *probably* wasting your time attempting to engage it in conversation. -- Greg -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
Hi, Am 22.01.14 12:01, schrieb lgabiot: Is it possible to link statically cairo to my extension, so that even if cairo is not installed on a computer, the code will run? I guess I would need to modify the setup.py file using distutils to compile cairo statically into my .so file? I've done it for a similar problem (linking HDF statically including its dependencies zlib and libjpeg), but I did write the Makefile by hand instead of using distutils. First, you need to compile a static version of cairo. I.e., you probably have got some libcairo.2.dylib or similar. This can't be used, you must end up with a libcairo.a archive, by passing --disable-shared --enable-static to the configure script. For this to work, the code must be position-independent (--with-pic in autoconf). This is a no-op on OSX, where all code is position-independent, but is important if you plan to port it to Linux. Then, during the linking step of your extension, you need to link against that statically compiled version of libcairo. In a Makefile, you would pass -L/path/to/thelibrary -lcairo to the compiler invocation for the linking step. I don't know distutils enough, but maybe you can either pass LDFLAGS to it to do this or directly point to that version of cairo. Or am I completely wrong? I'm a big fan of static linkage in that case, too. There might be another issue with the license of the library. Cairo is both LGPL and MPL. For LGPL, only dynamic linking is without doubt, for MPL it seems to be accepted to link statically. It all depends on whether you plan to pass on the binary to another person. To circumvent this problem, it might be feasable to just install libcairo along with you extension. Then, the exact same version of python must be used on both computers. Since the extension loading mechanism completely relies on the OS dynamic linker, it is not possible to load an extension into a different version of python than it was built for. Sadly, nobody implemented a system like Tcl's stubs, where an array of function pointers gets passed to the extension. This system allows to load an extension into later versions of the host program. Christian -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
Le 22/01/14 23:09, Gregory Ewing a écrit : We suspect that 8 Dihedral is actually a bot, so you're *probably* wasting your time attempting to engage it in conversation. Thanks, so that will be my first real experience of the Turing test!!! -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
thanks a lot for your very precise answer! shortly, as I'm running out of time right now: I've got here a lot of informations, so I'll dig in the directions you gave me. It will be a good compiling exercise... (I'm really new at all this). -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
On Thu, Jan 23, 2014 at 10:00 AM, Christian Gollwitzer aurio...@gmx.de wrote: There might be another issue with the license of the library. Cairo is both LGPL and MPL. For LGPL, only dynamic linking is without doubt, for MPL it seems to be accepted to link statically. It all depends on whether you plan to pass on the binary to another person. To circumvent this problem, it might be feasable to just install libcairo along with you extension. Then, the exact same version of python must be used on both computers. Since the extension loading mechanism completely relies on the OS dynamic linker, it is not possible to load an extension into a different version of python than it was built for. If you can tie in with your OS's package manager, that would solve all of these problems. You get the OS-supplied Pythom and the OS-supplied libcairo; grabbing libcairo-dev (or, on my Debian system, libcairo2-dev to go with libcairo2) gets you what you need to build your extension; you then might even package your extension the same way, and then simply declare dependencies. Can save a HUGE amount of trouble. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
Re: Using a static library in a C extension for Python
Le 23/01/14 03:33, Chris Angelico a écrit : On Thu, Jan 23, 2014 at 10:00 AM, Christian Gollwitzer aurio...@gmx.de wrote: There might be another issue with the license of the library. Cairo is both LGPL and MPL. For LGPL, only dynamic linking is without doubt, for MPL it seems to be accepted to link statically. It all depends on whether you plan to pass on the binary to another person. To circumvent this problem, it might be feasable to just install libcairo along with you extension. Then, the exact same version of python must be used on both computers. Since the extension loading mechanism completely relies on the OS dynamic linker, it is not possible to load an extension into a different version of python than it was built for. If you can tie in with your OS's package manager, that would solve all of these problems. You get the OS-supplied Pythom and the OS-supplied libcairo; grabbing libcairo-dev (or, on my Debian system, libcairo2-dev to go with libcairo2) gets you what you need to build your extension; you then might even package your extension the same way, and then simply declare dependencies. Can save a HUGE amount of trouble. ChrisA thank you very much for your answer, I'll work on your informations. -- https://mail.python.org/mailman/listinfo/python-list
