Quoth John Skaller, on 17 December 1998 [on whether the config module should be builtin or a separate .py file]:
I don't see any real choice: it has to be separate AND editable. Because if I download a binary Windows version, the information will be wrong for my system. The Unix version might be wrong too: perhaps I built Python with gcc, but I want to build extensions with ecgs, or with edg.
There are a number of reasons why you don't want to do this, and it all boils down to the fact that in the C world you cannot reliably link two object files if one was compiled with compiler X and the other with compiler Y. A concrete example that has burned me in the past: the 'assert' macro supplied with certain versions of GCC uses a function that is only available when you use GCC to drive the link, ie. when you the GCC runtime library is linked in. I have been bitten by this in two widely separated areas: distributing a C library that was used by ImageMagick and GIMP; people had problems if they compiled ImageMagick or GIMP with the system compiler and my library with gcc. Likewise, I have seen problems with a C library/Perl extension that I wrote; if someone manages to build the library and extension with gcc and link against a Perl built with cc, they stumble across this problem. (Less likely, because the SOP in Perl-world is to build extensions the same way Perl itself was built -- for this very reason, no doubt!) Similarly, different C++ compilers might use different name-mangling algorithms, again causing symbol mismatches. Anyways, these all constitute reasons for *strong recommendations* against fiddling with the compiler or flags. I'll concede that someone who *really* knows what they're doing should be allowed to do this (but they should also have to sign a disclaimer first ;-). And if they want to edit a machine-generated Python library to make this change permanent, well, again the responsibility rests on their shoulders. Extension builders should certainly have the option to override defaults from the config module, eg. ./setup.py build --cc=gcc --optimize=-g or ./setup.py install --prefix=/home/greg or something like that. (Fodder for another thread, perhaps.) However, I can definitely buy Andrew's and Robin's arguments in favour of [config-module-name].py rather than building it into Python. Greg -- Greg Ward - software developer gward@cnri.reston.va.us Corporation for National Research Initiatives 1895 Preston White Drive voice: +1-703-620-8990 x287 Reston, Virginia, USA 20191-5434 fax: +1-703-620-0913