Path: utzoo!yunexus!geac!daveb
From: daveb@geac.UUCP (David Collier-Brown)
Newsgroups: comp.unix.wizards
Subject: Re: ... and wild shell ravings
Summary: I had to write one in an Ada course.
Keywords: shell design, layering
Message-ID: <2950@geac.UUCP>
Date: 4 Jul 88 14:06:11 GMT
Article-I.D.: geac.2950
References: <889@esunix.UUCP>
Reply-To: daveb@geac.UUCP (David Collier-Brown)
Organization: The Geac "History is Bunk" Department
Lines: 37

In article <889@esunix.UUCP> bpendlet@esunix.UUCP (Bob Pendleton) writes:
| So what does this have to do with the claim that all the shells I know
| of are broken? Well... if shells were structured as an environment
| server, an input line editor, a command line interpreter, and a batch
| language interpreter (the last two could be one program) each a
| separate but communicating process, then I could have the input line
| editor I want and the command language I want. Mix and match to my desire.
| Each of these programs would be a single function program instead of a
| complex multifunction monolithic program.
| 
| I know that mach provides an environment server, is anyone working on
| a shell structured the way I've described? 

  One upon a time, I had to write a module of such a shell as part
of an Ada course (I did a spelling corrector/DWIM and didn't get
finished).
  The design problems are many and subtle, but the eventual
construct looked like a ring of "processors", each doing an
operation on a commandline and then indicating if it should go
"around the ring" again before being passed to the underlying command
loader.

  Its a **good** idea!

  It doesn't exist on may machines because the problems of an
integrated suite of independent functions/programs were poorly
understood when Unix was designed, and people have merely followed
precedent...

--dave (some things are hard. Others just look hard) c-b
ps: The inventor of the "ring" algorithm was Paul Stachour,
    Stachour@HI-MULTICS.ARPA  
-- 
 David Collier-Brown.  {mnetor yunexus utgpu}!geac!daveb
 Geac Computers Ltd.,  | "His Majesty made you a major 
 350 Steelcase Road,   |  because he believed you would 
 Markham, Ontario.     |  know when not to obey his orders"