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Date: Wed, 12 Apr 1995 13:42:54 +0200
From: "Hans ]berg" <haberg@MATEMATIK.SU.SE>
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To: Multiple recipients of list LATEX-L <LATEX-L%DHDURZ1.BITNET@vm.gmd.de>
Subject: Re: modularity
Status: R

  I want to note that there is an easy way to "objectify" TeX, without having to
do extensions of TeX itself:

  An object with name "X" is given command names of type "X/x" (backslahses "\",
as in "\X/x" excluded, since they should not be considered part of the name); a
subobject of X with name "Y" is then given the name "X/Y/x" (corresponding to
the command \X/Y/x), and so forth.
  Objects could be environments and packages.

  When you want to read a package, you first read the macro-definitions, as
usual. Secondly you make use of a set-paths mechanism. An environment that wants
to use commands from package X sets the path "X/", so that when the command \x
is entered, it first checks \X/x, and if that does not exist, it tries \x.

  I can think of two ways to implement this set paths function:
*1 The first is, instead of making use of \x, having a special command \do{x},
which reads the paths list.

*2 The second is having a command \set{X} which run through all the macros of X,
and is doing a \let\x=\X/x, after which \x can be used as normal.

  Since *2 is likely to be slow, *1 would be preferrable. Even better would be
to extend TeX itself, allowing such techniques.

  Anyhow, it is then easy to extract just the part that you want to make use of,
and combine packages which are variants on the same task.
  For instance, if you want to make use of the package "article", except for the
equation numbering, which should make use of the "report" format, then you can
write (symbolic code)
        \load{article}
        \load{report}
        \set{article}
        \let\theequation=\report/theequation

  One can think of refinements: For instance, the article and report packages
should probably have a superclass called "manuscript" with a more general
definition of \theequation (named "manuscript/theequation") which the article
and report packages set some variables to. Users could then easily do their own
variations of the \theequation command.

  Hans Aberg