Path: utzoo!mnetor!uunet!husc6!psuvax1!burdvax!bigburd!fritzson
From: fritzson@bigburd.PRC.Unisys.COM (Richard Fritzson)
Newsgroups: comp.editors
Subject: Re: lisp environments (Structure vs. text editors)
Message-ID: <3375@bigburd.PRC.Unisys.COM>
Date: 14 Dec 87 02:11:18 GMT
References: <487@PT.CS.CMU.EDU> <460@cresswell.quintus.UUCP> <499@PT.CS.CMU.EDU>
Sender: news@bigburd.PRC.Unisys.COM
Organization: Unisys Corporation, Paoli Research Center; Paoli, PA
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In article <499@PT.CS.CMU.EDU> ralphw@IUS2.CS.CMU.EDU (Ralph Hyre) writes:
>In article <460@cresswell.quintus.UUCP> pds@quintus.UUCP (Peter Schachte) writes:
>>Text editors CANNOT simulate structure editors.  They can do a rather
>>feeble job of it.  Text editors fall down when context information is
>
>I disagree - a PROGRAMMABLE text editor can do anything you want.  This is
>because it's programmable.  Whether you're happy with the performance or a

Sure it can do anything. The best way for a programmable text editor to
simulate a structure editor would be for it to build an internal 
representation (or structure) or what was really being edited and then 
use its text manipulating primitives to show the user the effect of his 
editing commands on the structure that is "really" being edited. Now you've
shown that mocklisp (for example) is a language in which you can implement
a structure editor. I doubt if it is the best way to do it though.

>>...For example:  a structure editor can supply different commands, different
>>facilities, for editing comments and code.
>Seems like there's the potential here for moby modefulness.  I can't see
>why I would want different commands when I edit code compared with comments.

I don't know about "commands", but Common Lisp comments are nothing
like Common Lisp code (much to the shame of Common Lisp). I want the
characters I type in as comments treated differently than those I type in 
as parts of S-expressions.

>My interest is in an pseudo-WYSIWYG editor which gives you the option
>of entering/editing text without formatting attributes, then optionally 
>displaying the text with them. <...>This sort of decoupling between editing a
>document and a representation of a document could even be used to great
>advantage in many environments:

You're right. An editor which is really editing the structure underlying
the visual presentation of it IS a useful thing. 

>	A program code editor might actually be showing you variable names,
>	statements, and S-expressions while it is really writing the P-code
>	(or .lbin file) on the fly.
>	This could result in 'instant' language interpreter facilities and 
>	fast compilers.
>	[I admit that this might be hairy to program in MockLisp.]

But it is one of the reasons Xerox structure editor fans are fans.

>[disclaimer: I've never used a 'structure editor' 

No offense intended, but I could tell. If you write any Lisp you should
look for an opportunity to try SEdit on a D-machine.




-- 
	-Rich Fritzson
	 ARPA: fritzson@prc.unisys.com
	 UUCP: {sdcrdcf,psuvax1,cbmvax}!burdvax!fritzson