Need an "environment" package
We need a package that plays the role of "toolchain" and provides a clean way for us to define environment variables that should be set for a clean compilation environment.
These are variables like
MACOSX_DEPLOYMENT_VERSION, that need to be set depending on the conda environment being used for building.
It makes no sense to have
bob.buildout or (even less)
bob.extension hosting those and having to change them at every interaction. Having these flags inside Bob makes the whole more "environment" specific and those should be portable to any environment. This includes builds with gcc or clang, for example. The person orchestrating the compilation should be setting these flags, not Bob, which is unaware of where and how it should be compiled.
A package distributed with Bob, with essentials for compiling Bob inside the relevant Conda environment is therefore quite the thing to do as it would relieve users from setting those variables by hand (or even knowing about them). It should just magically work.