On 29 May 2009, at 08:28, joaquin@tid.es wrote:
These are points for a lib developer to evaluate, not the Boost user. Remember we were talking of reasons why users prefer header-only.
Again, I've listed here my personal reasons (as a user). I think it could be instructive to try to gather more insight as to why our users prefer header-only libs, putting aside our own arguments as Boost authors.
I have looked through a number of interactions we have had with boost on my project's mailing list, to find exactly why we have been having problems with boost. I acknolwedge the current e-mail is extremely bias to UNIXy systems, I don't know about windows. The problems can be broadly split into two categories: 1) ./configure doesn't act "like configure" (as it's actually just a wrapper over bjam). This seems to have got much better of late, with the new ./bootstrap.sh making things much clearer. 2) compiling boost with a short command line is hard. If I want someone to compile using gmp and libz (for example) I tell them to drop "-lgmp -lz" on the end of the g++ command, or I hardwire '-lgmp -lz' into a tiny makefile. Assuming these two libraries are installed, that will cover 99% of systems I come across in common usage. Now lets imagine I want to include functional (a header-only library). #include <boost/functional.hpp> // Fails #include <boost-1_39/boost/functional.hpp> // Fails with bizarre errors So I have to add: -I/usr/local/include/boost-1_39 Which of course won't work if I then go to another computer, where boost isn't in /usr/local/include The problem is exacerbated by libraries, where I have to type (on my computer) -L/usr/local/lib/libboost_thread-xgcc40-mt-1_38.a This is little no chance of that line being valid on another system, and it's hard to describe to people how to generate it. In summation, I think the biggest problem I've had with boost is in the 'small simple problems' category. Two suggestions: 1) I've seen some systems provide a script which can be executed like: g++ my_file ` boostdefs --include --library ` Which produce the appropriate flags. Exactly how should a system should work is of course up for debate. 2) Why not provide a 'libboost' which includes all the libraries linked together. If they are dynamically linked this shouldn't create a large overhead. Chris