🚀 go-pugleaf

A while ago, someone made the radical suggestion that the GNU Project
should adopt Imake to make installation of its programs and libraries
easier.  I would like to make a somewhat different suggestion, one
which will make *programming* of GNU programs and libraries.

I would like to suggest that the GNU Project adopt the MIT Common
Error Description Library as its error-management system.  com_err
offers several advantages to the programmer:  all error messages are
kept in a separate file, foo.et, which is then processed to create
foo.h and foo.c (with the error numbers and messages, respectively);
all routines and libraries which use it have the same interface for
passing back errors and formatting error messages; Kerberos v5 and
many other MIT programs and libraries already use it, which means it
will be bundled with (at least) DCE.

The terms for use are New Berkeley, which should present no problems,
since GNU already uses several other packages, such as flex, which are
under those same terms; copyright is held by MIT SIPB.

Here is the abstract of "A Common Error Description Library for UNIX",
draft of 1 January 1989, by Ken Raeburn and Bill Sommerfeld:

	UNIX has always had a clean and simple system call interface,
	with a standard set of error codes passed between the kernel
	and user programs.  Unofrtunately, the same cannot be said of
	many of the libraries layered on top of the primitives
	provided by the kernel.  Typically, each one has used a
	different style of indicating errors to their callers, leading
	to a total hodgepodge of error handling, and considerable
	amounts of work for the programmer.  This paper describes a
	library and associated utilities which allows a more uniform
	way for libraries to return errors to their callers, and for
	programs to describe errors and exceptional conditions to
	their users.

The Common Error system is available from pit-manager.mit.edu.  It
consists (when compiled) of compile_et, the error table compiler, and
libcom_err.a, the library.  The library provides the following routines:

   com_err(const char *whoami, long error_code, const char *fmt,...)
    - prints whoami: error_message(error_code) vsprintf(fmt,args)

   com_err_va(const char *whoami, long error_code, const char *fmt,
	      va_list args)
    - prints the same as com_err, but for variadic functions

   error_message(long error_code)
    - returns the message corresponding to error_code

   set_com_err_hook(void (*)(const char *,long,const char *,va_list))
    - dynamically substitutes a routine for com_err_va (e.g., to call
      syslog instead of printf)

-GAWollman
Garrett A. Wollman - wollman@emily.uvm.edu

Disclaimer:  I'm not even sure this represents *my* opinion, never
mind UVM's, EMBA's, EMBA-CF's, or indeed anyone else's.