Patches and Symbolics

[rich@linus.MITRE.ORG]

	Date: Thu, 02 Mar 89 10:05:45 -0500
	From: kanderso@DINO.BBN.COM

	BBN and probably also others like Jim, have made patches to PCL in
	addition to the ones that come over the mailing list.  So any time we
	try to use a new version of PCL, we must carefully diff the sources
	and consider each change carefully.  Our approach has been to have a
	pcl-patches.lisp file that has all the patches in it.  It is loaded
	after all of PCL.  Patches that can be loaded after PCL are just there
	in the file.  

Here at Mitre we do something similar.  We have a system called Mitre-PCL
which contains all such patches, plus some home grown enhancements for PCL.
It also loads PCL automatically.  This has all of the advantages that
any patchable system does on a Symbolics, i.e., you can save the pcl system
in an incremental world, and then the patches to the system will be
loaded automatically when booting.

	Having patches in one mail file or directory might be a place to
	start.  That way you could compare the date of the patch to the date
	you snarfed PCL.

I vote for this as long as you continue to also put the patches in 
the original files.  Otherwise it would be necessary to "build" PCL
if you "snarfed" it late. 

Our mailer is very flaky right now, and we could avoid missing out on
some fixes but checking arisia every once in a while.