any *compelling* reasons to whitelist env vars for an OE build?

["Robert P. J. Day" <rpjday@crashcourse.ca>]

  kind of a philosophical question, but i'm having a discussion with
some new colleagues about how to customize an OE (actually, wind river
linux) build, and these colleagues have, until now, used (whitelisted)
environment variables to pass info to the build, that info being used
to specify things like a development versus manufacturing build, and
so on.

  i suggested that i didn't think there was any really persuasive
reasons to use environment variables this way, as there are more than
enough configuration files to customize a build. i mentioned things
like:

  * machine config files
  * distro config files
  * defining packagegroup files
  * defining image files

and on and on and on.

  my point was that there are more than enough ways to support all the
customization you might need, that taking advantage of shell
environment variables strikes me as unnecessarily messy and, for that
matter, dangerous if you forget so set the environment.

  thoughts? am i out of line in advising them to use what OE offers
them, and not extract stuff from the environment?

rday