Global variables...

[DBrown at HI-MULTICS.ARPA]

  The reason for get_thing() and set_thing() have little if anything to
do with religion, (unless Dave Parnas decides to start his own church),
but do have to do with maintainability.
  If I "hide" the implementation of the error-reporter inside a pair of
globally-accessably functions, I have a simple way of changing the
implementation:  I install a new version of get/set in the library
search order, and everyone who links a new program gets the new one.
  The "global variable" implementation tends to be a nuisance when one
has to continue to maintain something when the requirements (hardware!)
changes.
  --dave (all bow down to the altar of maintainability) brown