CET1@phoenix.cambridge.ac.UK (03/06/88)
(Third time lucky... I have been trying to send this message to info-postscript@edu.stanford.sushi (I know that's backwards for you USA types) but the uk.ac.ucl.cs.nss gateway seems to have a hate relationship with edu.stanford.sushi. I am trying edu.stanford.navajo instead. Apologies for the out-of-date'ness of the contents.) In article <1567@uhccux.UUCP> Greg Lee <uhccux!lee@mil.nosc.humu> writes > PS code enclosed in braces is specified as compiled. That might mean > pseudo-compilation or compilation to machine code. I wrote a subset > implementation for PS, ... "Specified as compiled"? Not in the red book, it isn't! The braces generate an executable array, but you might never execute it. Also (unless you use setpacking) it is writable; it can be patched before being executed; or indeed changed each time. Yes, I know, that's the style of the self-modifying assembler hacker, but a real PostScript inplementation would have to allow for it, wouldn't it? There seem to be a lot of these subsets about... a little longer ago in article <19765.8801291430@vd.rl.ac.uk> Crispin Goswell <mcvax!vd.rl.ac.uk!caag@net.uu.uunet> wrote > This is to announce an independent implementation of the PostScript > page description language for previewing on graphics workstations. > ... > It is a complete implementation with the exception of > save and restore and readonly and executeonly. Well, I don't want to carp, but I can't imagine a serious PostScript application that wouldn't use save and restore. By the way, does anyone from Adobe watch this bulletin board these days? It seems a long time since we had a posting from them. Chris Thompson Cambridge University Computing Service JANET: cet1@uk.ac.cam.phx ARPA: cet1%phx.cam.ac.uk@nss.cs.ucl.ac.uk
caag@vd.rl.ac.UK (Crispin Goswell) (03/08/88)
Chris Thompson wrote: >Well, I don't want to carp, but I can't imagine a serious PostScript >application that wouldn't use save and restore. You might be surprised. I'm sure plenty of people can find examples where these operators are used, but many of the major text processing and diagram applications, make only trivial use of the power of save and restore. This is of course a generalisation... :-) My interpreter has managed without for quite a while now. I've had other comments about it, but very little said about save and restore. Most interpreters are incomplete because the language is not trivial to implement. Freely available interpreters (such as mine) are likely to be more incomplete than those people charge money for (such as Adobe's), for obvious reasons. - Crispin Goswell