Re: Post-22.1 development?

[Richard Stallman]

    There are two clean ways to do this is: (i) extend process-environment
    so that if a symbol occurs in the list, as opposed to a string, that
    symbol names a list whose elements are to be used (as though they had
    been inserted in process-environment).  Then the final element for all
    default values of process-environment would include the symbol
    `global-process-environment'; or (ii) extend process-environment so
    that an element of `t' means "the global value of this variable"
    (similar to hook variables).

These are more elegant, but I am not sure it matters in practice.

    Either of these approaches would be backward compatible for
    third-party than the shared-tail idea, but IMHO the gain in
    cleanliness more than makes up for it.

I don't think so, and the reason is that this won't clean
up the code in Lisp programs at all.  On the contrary, it would
complicate them.

In other words, elegance of the mechanism is not the same thing
as simplicity of the user code.

We use method ii for hooks, but the complexity is hidden inside
two standard functions.