Path: utzoo!yunexus!geac!daveb
From: daveb@geac.UUCP (David Collier-Brown)
Newsgroups: comp.software-eng
Subject: Re: Question Re: Configuration Management
Summary: Side discussion on Linkers/Statics
Keywords: linkers, software design, Unix as a religion
Message-ID: <2323@geac.UUCP>
Date: 24 Feb 88 13:53:55 GMT
Article-I.D.: geac.2323
Posted: Wed Feb 24 08:53:55 1988
References: <497@aimt.UUCP> <2640@ihlpe.ATT.COM> <188@dinl.mmc.UUCP> <213@ritcv.UUCP>
Reply-To: daveb@geac.UUCP (David Collier-Brown)
Organization: The G. Yac Linker Department.
Lines: 58


  Gentlebeings,
	Unix is not the be-all and end-all of creation.
	Unix is just better IN THE MAIN than its competition.
  Now, on to the substance of the discussuion:

In article <213@ritcv.UUCP> mjl@ritcv.UUCP (Michael Lutz) writes:
>And, for the person who complained about the brain damaged Unix linker and
>librarian: most linkers I've encountered have the same restriction.
>The library contains object modules, possibly with multiple entry points,
>and if you reference one you get them all.  It's damn difficult to pull
>apart an object module and decide which bytes you need and which ones
>are extraneous.  The Unix linker/librarian may not set the world on fire
>with it's snazzy features, but it most certainly is state of the practice.


In article <2984@metavax.UUCP> chris@metavax.UUCP (Chris Collins) writes:
>	BTW Unix is THE system, for programmers or otherwise, it does
>have one obvious drawback: it assumes the user is competent.  The idiocy
>you speak of is not with system!  A lobotomy in your case is not necessary.

   Both Mike (politely) and Chris (substantially less so) miss the
point that the Unix linker was a conscious cheap-and-dirty.  The Multics
system avoided the whole IDEA of static linkers[1], and most if not
all commercial systems not derived from Unix have better linkers.
Good Lord, the IBM /360 had a better linker than Unix! (And I
wouldn't recommend the /3sickly and its linker to my worst enemy).  

   In order to learn C, a non-unix programmer of my acquaintance
ported a subset compiler (Ron Cain's Small C), and taught it to
generate code for his assembler/linker set, placing each function in
a linkable "procedure record", and emitting "symref records" for all
externally required datums of the function, including a symref to a
(specially named) record which contained the static data for the
module (ie, the file-level statics).  

  Not hard at all.  A suitable project for learning the language...

In pseudo-linkeese:
DSECT _.filename
	DW 1	    ; static int foo; /* A file-level static */
SYMDEF _function
CSECT _function
	LD A1,Sp    ; function(p,q) char *p, *q; {
	LD D1,_.filename+0 ; if (foo) {
	...
SYMREF _.filename

--dave (those who know not history.... piss me off) c-b

[1] It had a thing called "binder", which produced
    almost-fully-resolved modules, more or less for use as
    efficiently-loadable public libraries.
-- 
 David Collier-Brown.                 {mnetor yunexus utgpu}!geac!daveb
 Geac Computers International Inc.,   |  Computer Science loses its
 350 Steelcase Road,Markham, Ontario, |  memory (if not its mind) 
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