SABBUS is the name of the Ant build script used to compile Scala. It is mostly automated and takes care of managing the dependencies.
LAYERS:
In order to guarantee the bootstrapping of the Scala compiler, SABBUS builds Scala in layers. Each layer is a complete compiled Scala compiler and library. A superior layer is always compiled by the layer just below it. Here is a short description of the four layers that SABBUS uses, from bottom to top:
'starr': the stable reference Scala release which is shared by all the developers. It is found in the repository as 'lib/scala.compiler.jar' and 'lib/scala-library.jar'. Any committable source code must be compiled directly by starr to guarantee the bootstrapping of the compiler.
'locker': the local reference which is compiled by starr and is the work compiler in a typical development cycle. When it has been built once, it is “frozen” in this state. Updating it to fit the current source code must be explicitly required (see below).
'quick': the layer which is incrementally built when testing changes in the compiler or library. This is considered a actual new version when locker is up-to-date in relation to the source code.
'strap': a test layer used to check stability of the build.
DEPENDANT CHANGES:
SABBUS compiles, for each layer, the Scala library first and the compiler next. That means that any changes in the library can immediately be used in the compiler without an intermediate build. On the other hand, if building the library requires changes in the compiler a new starr (or in some case only locker if bootstrapping is still possible) compiler must be built in-between.
The Scala build system is based on Apache Ant. Most required pre-compiled libraries are part of the repository (in 'lib/'). The following however is assumed to be installed on the build machine:
