Subject: [[email-masked]: Extension Languages...]

From: [email-masked]
Date: Fri, 3 Apr 87 02:57:21 EST

Date:  2 Apr 87 08:56 EST
From: [email-masked]
Subject: Extension Languages...
To: [email-masked]

Date: Thu, 2 Apr 87 08:36:11 EST
From: putnam <putnam%thuban.tcpip@csbvax>
To: [email-masked]
Subject: Extension Languages...

>> There is no statement anywhere that extension code has to be already linked
>> into an X server.  A lisp-based X server might very well load code on the fly>> and a C-based server might also, if C implementations were only up to it.

>In fact you could certainly do that on any system that has dynamically
>loadable code (an Apollo for instance :-).  That kind of issue is really
>independent of the particular server.  In the case of NeWS we have a
>server that has chosen to make such loading explicit, at the cost of making
>you use its own language.  In the case of X it would presumably be
>available as an extension not bound to any particular language - at the cost
>of portability but a potential gain in functionality.  Dynamic binding and
>global libraries solve a large number of problems (not the least of which
>being lack of disk space due to large object modules), but the solution to
>that shouldn't reside in a window server, but in the system implementation as
>a whole.

I think there is a problem with this notion.  If server A (say a Symbolics)
uses lisp+new flavors as an extension language and something is developed
in it, there is no guarantee that it will ever run on server B.  Server
B may even be a lisp machine, but not have a completely compatable object
oriented extension to lisp running on it.  Yes, this was said above
"at the cost of portability", but from where i sit, portability is one
of the major issues - and i thought that one of the driving forces for
X was portability and standardization.

Thus it seems to me that any extension language for X should be defined
by the X community and standardized.

A question is whether or not PostScript is a good language for window
tools to use as an extension language.  I think i would claim that it is.
It is fairly small and simple enough that the language processor can be
quite simple.  It is probably small enough to be implemented in
hardware.  Despite its simplicity it is very powerful, and although
dealing with the stack can be difficult at times, easy to program in.
The object oriented extension was a natural thing to do, given the
structure of PostScript, and a very helpful one to have.

I readily admit to a bias in favor of NeWS - despite having had some
problems with it.  This is partly because i once wanted to build
(in a different context) something very similar, and partly because
it is a real nice system.  (Sun did a much better job with NeWS than
i would have with my system, but i was aiming at a much smaller target.)

Well, shall we go?  -- jefu (jeff putnam)
Yes, lets go.       -- UUCP: steinmetz!putnam
(They do not move.) -- ARPA: [email-masked]