[Distutils] Is build an inherently arbitrary-code process?

[Daniel Holth]

I became convinced that build was an inherently arbitrary-code
process, and not something to be universally handled by a declarative
system, when I observed an autotools project under configuration. The
things spend ten minutes writing and compiling snippets of C code to
determine which features are and are not supported by the runtime.
This is *very* arbitrary code and probably one of the tamer things
people like to do during builds.

As usual I blame distutils, because the separation is not there. So
when you blame setup.py for having to run procedural code to generate
the *metadata* you might go to far and think you should also eliminate
a procedural build - simply because build and metadata are not
adequately separate in the distutils design. Declarative build systems
are a nice idea but they are not going to work for everyone.