[EROS-Arch] Package handling...

[Ben Laurie]

Bill Frantz wrote:
> 
> At 12:19 PM -0800 3/28/01, Joerg Bornschein wrote:
> >
> >How did uninstallation work in KeyKOS?
> 
> For system-wide installations, we followed Alan Karp's approach and kept
> the old versions.  For test installations, we just blew away the space bank
> and let the null keys fall where they may.
> 
> In one case, we actually replaced the code segment of a running system-wide
> class of objects.  Since the objects were not designed from the start for
> upgrade, the binary code patch was very delicate.  With forethought, it is
> possible to build objects which check if an upgrade is available and
> automatically upgrade themselves.  It requires a lot of thought about the
> necessary data conversions, and how you maintain compatibility.  That level
> of thought is probably "good for you", but no one that I know is in the
> habit of thinking that way.

I once wrote a system that did data versioning and upgraded lazily
(through all intermediate versions) when the data was next used. Natch,
it included serialisation in order to do this! (The target language was
C, btw).

Cheers,

Ben.

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