don@brillig.umd.edu (Don Hopkins) (09/21/88)
Date: 20 Sep 88 14:53:14 GMT
From: phri!roy@nyu.edu (Roy Smith)
Subject: Why you shouldn't use NeWS as a tool to learn PostScript
[...]
I still maintain that NeWS is different enough from PostScript to
make in inadvisable to use the former as a tool for learning the latter.
--
Roy Smith, System Administrator
Public Health Research Institute
{allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
"The connector is the network"
My argument, which applies to interpretive languages in general, is
that it's easier to learn a language in an interactive programming
environment than in a batch environment. Direct access and immediate
feedback gives a programmer immersed in an interpretive environment
intimate experience with the language, and incentive to experiment.
The problems that you describe are minor compatibility issues, not
fundamental learnability issues.
PostScript is very different than the languages most people are used
to. The syntax of PostScript is extremely simple, but if you're ever
going to be able to harness its power, you've got to understand the
semantics. And playing around with an interactive interpreter is a
quick and fun way to find out how it works.
The fact that the PostScript interpreter in NeWS is different than the
PostScript interpreter (whatever brand it is) that runs in your laser
printer doesn't mean that it's harder to learn PostScript in NeWS. Of
course NeWS is different: it has extensions, and it has bugs. But the
fact that NeWS is an interactive programming environment that can give
immediate visual feedback on the screen is a far more important issue
to someone interested in learning a new language.
Metaphorically, I'm saying that it's better to learn Spanish by living
in Spain, than by writing letters to people in Spain. You're saying
that it's inadvisable to learn Spanish by living to Spain, if you want
to write letters to people in Mexico. c(-;
-Don
don@brillig.umd.edu
...!uunet!mimsy!donlee@uhccux.uhcc.hawaii.edu (Greg Lee) (09/22/88)
From article <13655@mimsy.UUCP>, by don@brillig.umd.edu (Don Hopkins): "... " going to be able to harness its power, you've got to understand the " semantics. And playing around with an interactive interpreter is a " quick and fun way to find out how it works. Maybe not all readers of this discussion know that you can do a certain amount of playing around without NeWS. The PS interpreter inside the Apple LW, at least, has an interactive mode. You can can have it calculate and display values on your screen, so long as the values have string values. For images, you have to wait for a page to print, though, so that slows things down. Greg, lee@uhccux.uhcc.hawaii.edu
walters@community-chest.mitre.ORG (Chris Walters) (09/22/88)
Plus, just think of all the paper you save using NeWS :-)
-- Chris
--------------------------------+------------------------------------------
Chris Walters | walters%community-chest@gateway.mitre.org
The Mitre Corporation, W97-z665 | walters@mitre.arpa
7525 Colshire Drive | (703) 883-6159
McLean, VA 22102 | Standard Disclaimer Applies
--------------------------------+------------------------------------------rminnich@super.ORG (Ronald G Minnich) (09/22/88)
In article <13655@mimsy.UUCP> don@brillig.umd.edu.UUCP (Don Hopkins) writes: >The fact that the PostScript interpreter in NeWS is different than the >PostScript interpreter (whatever brand it is) that runs in your laser >printer doesn't mean that it's harder to learn PostScript in NeWS. Of Actually, there is one problem with playing with NeWS that i have found. You screw up, and you blow your window manager out of the water. Then it is almost impossible to determine the state of the world, given that you have canvasses floating around that have no (seeming) process attached to them, and you can't change your focus, and ... I would much prefer having an X window with a PS interpreter in it for learning. Then i only have to worry about blowing up that window, not my whole server. I liked NeWS a lot, but it is too fragile. Sure, it has lightweight tasks and all that other nice event handling built in. When i started learning it it really looked like the 'right way to go'; in fact, it still does. Sometimes there is a difference between the right way to go and the thing that works. I think X11 works. For example, NeWS has no protection. You can just go trash the interpreter's universe and then find yourself in a very unhappy state without a paddle. No fun. I have yet to trash the X server in the ways i trashed the NeWS server. It could be that NeWS is just running under the wrong OS. A good impedance match of NeWs to OS would be a NeWS on the amiga, as much of what NeWS does (event queues, lightweight tasks, etc.) has an almost eery resemblance to what the amiga Rom Kernel and Intuition support. And the same problems exist, too, the biggest being no protection. Maybe NeWs would be better under Mach ... ? I notice that there have been comparisons of NeWS to Unix, in the sense that NeWS represents a technically superior system much as Unix one time represented a technically superior system that might not have caught on. There is one key difference. By the time Unix really started to catch on, it was no longer technically superior. In fact nowadays we are more bound by its limitations than overawed by its abilities. If i had to compare NeWS to an OS, i would compare it to the Apollo Domain system or Multics, which are technically superior but have also remained vendor-specific and hence something of a niche system. I think the analogy that really holds is Unix --> X11, Multics --> NeWS. And we all know which OS 'won' in the sense of being 'universal'. We also have a pretty good idea which is better, i think ... ron
john@trigraph.UUCP (John Chew) (09/22/88)
In article <2407@uhccux.uhcc.hawaii.edu> lee@uhccux.uhcc.hawaii.edu (Greg Lee) writes: >Maybe not all readers of this discussion know that you can do a >certain amount of playing around without NeWS. The PS interpreter >inside the Apple LW, at least, has an interactive mode. You can >can have it calculate and display values on your screen, so long >as the values have string values. For images, you have to wait >for a page to print, though, so that slows things down. > > Greg, lee@uhccux.uhcc.hawaii.edu If you have a Mac, another good way to learn PostScript is to buy a copy of LaserTalk, by Emerald City Software (with whom I have no connection, other than by virtue of being a satisfied customer). LaserTalk is a PostScript programming environment with basic debugging features (breakpointing, stepping and tracing through code, dictionary browsing, continuous display of a user-configurable set of status variables), a reasonable editor, and an online hierarchical copy of the operator summary in the Red Book. You can also preview a page image on your screen at varying resolution without running off hardcopy. I could not do any serious PostScript work without LaserTalk or something like it. Programming PostScript blindly and running off hardcopy to test it is an obscene idea from the dark ages of batch programming and punched cards. Connecting a terminal to a LaserWriter and talking to its interactive interpreter is still a pretty sick idea. It's like debugging a graphics program in C without a debugger or a raster device. I wish I had an opinion on NeWS, but that'll have to wait until we get a Sun here.... John Chew -- john j. chew, iii poslfit@utorgpu.bitnet trigraph, inc. poslfit@gpu.utcs.toronto.edu toronto, canada {uunet!mnetor!utzoo,utgpu,utcsri}!trigraph!john [it is my opinion that these are solely my opinions.]