* Conditionals and variables in Fix expressions. This allows, e.g.,
Descr(
[ Bind("pkgId", "subversion-0.21.0")
, Bind("httpsClient", Bool(True))
, Bind("httpServer", Bool(True))
, Bind("ssl", If(Var("httpsClient"), Fix("./openssl-0.9.7b.fix"), ""))
, Bind("httpd", If(Var("httpServer"), Fix("./httpd-2.0.45.fix"), ""))
...
])
which introduces domain feature variables httpsClient and httpServer
(i.e., whether Subversion is built with https client and webdav
server support); the values of the variables influences package
dependencies and the build scripts.
The next step is to allow that packages can express constraints on
each other. E.g., StrategoXT is dependent on an ATerm library with
the "gcc" variant enabled. In fact, this may cause several
Nix instantiations to be created from a single Fix descriptor. If
possible, Fix should try to find the least set of instantiations
that obeys the constraints.
build action for `system' packages (like system.fix) that have
dependencies on all packages we want to activate.
So the command sequence to switch to a new activation configuration
of the system would be:
$ fix -i .../fixdescriptors/system.fix
...
system.fix -> 89cf4713b37cc66989304abeb9ea189f
$ nix-switch 89cf4713b37cc66989304abeb9ea189f
* A nix-profile.sh script that can be included in .bashrc.
