[BBv2] sorted property lists

From: Christopher Currie (Christopher_at_[hidden])
Date: 2004-01-29 17:06:12

I've been struggling recently with what seems to be a recent change to 
BBv2, in that property-lists are now kept in collation order. This 
causes problem when you need to guarentee that one property has effect 
before another.

An example: a machine comes with a system curses library that is old and 
broken, so I want to use a replacement libcurses, which I have installed 
in /usr/local/lib. but I also need to link against another library (say, 
pthread) in /usr/lib, which also has my system's broken curses.

So my project would look something like:

project my/project ;

CPP_SOURCES = foo.cpp bar.cpp ;

lib libcurses : : <name>curses <search>/usr/local/lib ;

lib libpthread : : <name>pthread <search>/usr/lib ;

exe app : $(CPP_SOURCES) libcurses libpthread ;

When I run bjam against this, my <search> properties get sorted, such 
that /usr/lib is put before /usr/local/lib. So my command line now ends up:

g++ -g -L"/usr/lib" -L"/usr/local/lib" ...

So my build picks up the wrong library. From what I can tell, there's no 
way to circumvent this, even by putting an explicit <library-path> 
property on the exe, because the sorted property list picks up the 
duplicate and throws it away.

This problem also effects library ordering, which I know is not 
implemented yet, but I could work around it before by making sure my 
libraries were listed in the proper order in the exe rule. Now, if 
libpthread (for example) were to depend on libcurses (obviously they 
don't but bear with me), I'd have no way of making that happen, because 
they'll be sorted on the command line.

Any thoughts? I personally can't see any way around it other than not 
sorting property lists, but perhaps I'm missing something.

Thanks,
Christopher