Re: Pre-processing during build

The discussion has veered off topic somewhat with the discussion of build
systems and their respective qualities.

My pull request is proposing to change build system from Ant to Maven. All
existing functionality in the Ant build has been/will be replicated in the
Maven build - including the pre-processing step. There are many advantages
to using Maven as opposed to Ant. However, this is orthogonal to the
discussion I'd like to have about the pre-processing used during the build
process.

Focusing on the aim of the current pre-processing step - which is to select
the appropriate spec implementation at compile time. The options seem quite
complicated to me as a relative novice in the finer points of the language
spec.

Taking a step back, could this not be achieved using annotations and a
custom annotation processor to emit some code to select the correct
implementation of the spec? This seems more Java-like and not a massive
change from the existing code.