Issues: IN-PACKAGE-FUNCTIONALITY and DEFPACKAGE

[Jon L White <jonl@lucid.com>]

In Kent's note of Tue, 27 Sep 88 12:25 EDT, he points out the action 
of MAKE-PACKAGE, for an existing package, is to "break" (in most
implementations.)    It occurs to me that the DEFPACKAGE proposal
is silent (hence, subject to varying interpretations) about how to 
handle the case of defining a package on a name that already exists.
I see three possibilities:

  (1) "break", just like MAKE-PACKGE
  (2) Simply do the new definition (as DEFUN and DEFCLASS do), possibly
      issuing a warning message based upon vendor-specific facilities.
  (3) Quietly do the new definition, providing that it is essentially
      compatible with the old one; signal an error if not compatible.

I think I'd prefer (3), since it allows you to re-load a file that
is under development, without getting spurious breaks or warning
messages; yet it provides some assurance that you aren't about to
break your whold world.

Comments?


-- JonL --