RE: alist-get in Emacs 24?

[Drew Adams]

> Second, yes, you could modify the list structure, but this can't be
> done if the alist is empty, because the empty (a)list is not a cons.
> At least in this case, your setter would still have to receive a symbol.

I don't see it that way.  How is this different from defining
`delete' or any of the other structure potentially-modifying
functions?  None of those functions require you to pass a symbol
argument.  The only function I can think of offhand that does
that is `add-to-list'.  Its more common (and generally more useful)
cousins, `push' and `pushnew' don't do that.

Yes, with such (destructive) functions, if you have a variable
pointing to the list (empty or not), you do need to re-set it
to the result returned by the function.  But that's all, AFAIK.

As I said (examples):
 (setq THE-VAR (my-set-alist-value key alist value))
 (setq foo (delete 42 foo))