Andrew writes (among other things):
> ....
> A few thoughts on multiple versions...
>
> Right now, Linux is mostly being used in low-end servers (e.g. web
> servers) and on desktops, but it's pushing up towards higher-end servers
> (and paradoxically down towards mobile computers), so while in the short
> term it's reasonable to consider Linux to mean desktop, it's probably
> unwise to make long-term plans based on that assumption.
>
> On the other hand, while Linux is still a mostly desktop phenomenon, we
> can assume that users will probably only want one version of Poplog on
> their system.
If you had lived through several versions of Poplog you might be
less confident of that! Most of the time changes are introduced in
such a way that things are backward compatible. However occasionally
there are major changes that cause a number of things in user
programs to break, e.g. when the default for procedure input and
output locals was (rightly) changed to be lvars rather than vars.
When such changes occur you may want to keep the old version around
while you learn about the new version and check out and modify your
programs. Sometimes you may need to be able to check whether an
unsolved problem is due to the changed version, by running your code
in both the old and the new, to see if it still works in the old.
Or you may wish to compare sources or documentation.
But I agree that many users will wait till other more expert users
have confirmed that changing is a good idea and then they will do it
and without keeping two versions going even for a short time.
> ...
> Finally, is there (and if not, I think there should be) a
> poplog_version (or similar) variable? That would make it possible to
> write a single set-up script that could handle multiple versions of
> poplog.
It's a pop-11 variable, set in the file $popsrc/initial.p
155300 -> pop_internal_version;
The value of popversion is derived from this (I am not sure where
or when):
popversion =>
** (Version 15.53 Mon Jul 12 19:45:02 BST 1999)
It occurs to me that it might be preferable to have a file called
system_version in $popsys, containing the value to be given to
pop_internal_version when poplink is invoked.
Aaron
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