Path: utzoo!attcan!uunet!husc6!mailrus!ames!oliveb!tymix!antares!jms
From: jms@antares.UUCP (joe smith)
Newsgroups: comp.sys.amiga
Subject: Re: ENV: variables (long)
Summary: grouped vars
Keywords: global vs local variables
Message-ID: <151@antares.UUCP>
Date: 10 Sep 88 07:58:04 GMT
References: <8809090740.AA16138@cory.Berkeley.EDU>
Reply-To: jms@antares.UUCP (joe smith)
Organization: Tymnet QSATS, San Jose CA
Lines: 44

One interesting non-Unix OS has 4 levels of variables; 2 on disk, 2 in
memory.  The order search is:
  1) Check memory for definitions local to the current CLI
  2) Check memory for definitions global to all CLIs from this session
  3) Read user's permanent defaults from ~/vars/*
  4) Read system-wide defaults from /vars/*

The set-variable command modifies only the local variables unless the
-global option is used, in which case the new value is visible to all
CLIs that were created by the current logon session.

When a new CLI is created, it inherits a copy of its parent's local
variables.  The new CLI cannot modify its parent's local variables, and
cannot see any change to its parent's local variables, but it can see the
session-wide global variables if it chooses to.  The routine to lookup
a variable will find the local value if one is defined, otherwise it
will find the global variable.  A program can explicitly request the
global variable (bypassing the corresponding local value) if it wants.

Global variable names are uppercase, local variables are lowercase.
Generic variable names are a single word.  Group variables are in the form
"groupname.varname" and are initialized from the file ~/vargroupname the
first time they are referenced.  Shell variables are of the form "shell.*"
(such as "shell.path=(/usr/bin /usr/local/bin"), which is better than
the Unix convention.  Instead of storing compiler options in names like
FOOBAROPTS, names like FOOBAR.WIDTH, FOOBAR.LINESPERPAGE, FOOBAR.MODE are
possible.  The command "list-var FOOBAR.*" lists only the FOOBAR variables.

I would like to see something like this on the Amiga.  In particular:
 1) Global variables visible to all tasks.
 2) Local variables per process, copied from parent when process is
    created and easily located.
 3) Routine to lookup a variable will find the local value if defined,
    otherwise automatically search for the corresponding global value.
 4) The ability to see both the local and global settings of the same
    variable if desired.
 5) Explicit grouping of variables, such as "groupname.varname", fully
    supported by the OS.

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