On Wed, Jul 9, 2008 at 9:04 PM, mabshoff <[EMAIL PROTECTED]> wrote: > > On Jul 9, 8:18 pm, "William Stein" <[EMAIL PROTECTED]> wrote: >> On Wed, Jul 9, 2008 at 8:11 PM, David Philp <[EMAIL PROTECTED]> wrote: > > Hi, > >> > This is a 'for the record' email describing how to use boost.python >> > with sage on Mac OS X. Thanks to the gentlefolk who walked me through >> > it (especially Carl Witty). >> >> > I am assuming a working boost.python extension called 'my_ext.so'. >> > "Working" means that you should be able to start up python at the >> > command line, run "import my_ext" and call your functions / >> > instantiate classes etc. >> >> > Attempting to do the same with sage fails. Start sage, run "import >> > my_ext" and it will fail with a message like >> > ImportError: dlopen(./my_ext.so, 2): Symbol not found: >> > _PyUnicodeUCS2_AsWideChar >> >> > The problem is that the version of python distributed inside sage uses >> > UCS4 (for consistency with linux) rather than UCS2 (which is used by >> > Apple's system python). Because libboost_python is compiled against >> > Apple's Python, it assumes UCS2. There are two possible fixes: (1) >> > recompile boost against sage's python, and it will use UCS4. (2) >> > Recompile sage to use UCS2. >> >> > The second option is better for me, because I want my python >> > extensions binary compatible with both system python and sage python. >> > (The alternative is to have system & sage versions of boost, and >> > system & sage versions of every extension.) Changing sage's default >> > unicode setting might have consequences that I don't understand, but I >> > haven't been bitten yet. >> >> It should be fine. We used UCS2 until maybe 8 months ago. We switched >> as mentioned above only for Linux compatibility. >> >> > You will need to do this for each successive >> > version of sage, which could be tedious. >> >> I would be ok with making an environment variable, e.g., SAGE_UCS2 >> that if set causes SAGE to build using UCS2. > > I don't like this at all since it will introduce more complexity and > the possibility for subtle bugs.
I'm ok with it but you aren't which is enough to make it definitely not OK. > >> Alternatively, we could make Sage on OS X use UCS2 but Sage on >> Linux use UCS4. > > I like this even less since Apple's python is universal and when you > build extensions with it those extensions are universal (or the > compiler at least attempts to build them). Since gmp is fundamentally > broken as a universal library due to design issues subtle bugs crop > up. I can quote one email from gmp-devel if you want me to. In > addition Apple's linker happily links together x86 code and ppc > libraries as I learned the other day and it took a long, long time to > figure out why an extension build that way failed to import at run > time. It is just not worth the trouble. We will switch to Python 2.6 > at some point and Apple might now follow. What to do then? Maybe their > next universal binary will be four arches instead of two now? As is > the 64 bit Sage port on OSX is fundamentally incompatible with any > python Apple ships. All good points. Your main point being -- screw worrying about any compatibility between Sage and the system-wide Python. > This is more general: If you want to use Sage with the system's python > you are on your own IMHO. The complexity to debug problems is insane > since you never know how python was compiled and when the user did use > the system python and when Sage's. Good point. You're preaching to the choir here. > Switching back and forth will > happen and make it even more murky. I don't mind that people do use > the system python or use custom build options if they know what they > are doing, but people have and will shoot themselves in the foot and I > have little time to help them since I have plenty of bugs to fix in > "vanilla" Sage. It is the old open source mantra: If you break Sage by > doing something stupid you get to keep the pieces :) - and we should > not encourage people to do something stupid. You're right. william --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
