RCS and SCCS

[John F. Haugh II]

In article <8158 at brl-smoke.ARPA> gwyn at brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes:
>In article <661 at pyuxe.UUCP> mayerar at pyuxe.UUCP (80132-A Mayer) writes:
>>One good point of RCS is that it stores the most recent version and 
>>uses deltas to get back to the previous versions.  SCCS stores the
>>original version and uses deltas to get to the most recent version.
>
>No, it doesn't.  I don't know who started this myth, but it's false.
>SCCS makes one sequential pass to do a "get".

just because get(1) only makes one pass over a file does not mean
the SCCS file is stored in most-recent-version order.  since it is
possible to know which versions the desired version depends on,
get(1) can follow the insert/delete commands in the s-file to create
the desired version.

if i start off with a file which reads

Now is the time for all good men.

and put it in an SCCS file, the results, sans extra cruft is

^AI 1
Now is the time for all good men.
^AE 1

and then you create a delta to make the file

Now is the time for all good men.
To come to the aid of their party.

you end up with

^AI 1
Now is the time for all good men.
^AI 2
To come to the aid of their party.
^AE 2
^AE 1

since the body for version 1 (as bracketed by the ^AI 1/^AE 1 pair) contains
the text for version 2, i would say that SCCS does indeed store the original
version and newer deltas.  the other way would look like

^AI 2
Now is the time for all good men.
^AD 1
To come to the aid of their party.
^AE 1
^AE 2

- john.
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