RE: [External] : Re: (interactive) and &optional

[Drew Adams]

> it might also be that you are interning the empty string,
> which creates a symbol with an empty string as the symbol name -- which
> is not unique.

What do you mean by "is not unique"?

> > Does an empty symbol have an external representation like an empty list or 
> > string, allowing the use of "eq"?

Yes: ##

(setq foo (intern ""))

C-h v foo

  foo's value is ##

(symbolp '##) ; => t
(symbolp foo) ; => t

(symbol-name '##) ; => ""
(symbol-name foo) ; => ""

(setq ## 42) ; or (set foo 42)

(symbol-value '##) ; => 42
##                 ; => 42

(But note that `C-h v ##' doesn't "work".)