RE: why does `variable-at-point' return 0?

[Drew Adams]

ping

> Just curious.  Why doesn't `variable-at-point' return nil if 
> there is no variable at point?
> 
> All I can think of is that for some reason someone wanted to 
> test using `symbolp' instead of testing using `not' (or `and').
> But I cannot imagine why.
> 
> Checking how `variable-at-point' is actually used in the 
> source code did not enlighten me.  Each use just checks whether
> the value is `symbolp' and goes on from there.  An actual value
> of zero is never used AFAICT, except to serve as a non-symbol.
> 
> There is no special need to distinguish nil from any variable - in 
> Emacs Lisp you cannot give the symbol nil a symbol-value other than nil.
> 
> It is true that (boundp nil) is true, so `boundp' is not a 
> test of variableness.  But I don't see why it wouldn't be just as
> easy to test whether the value is nil instead of testing whether it
> is a symbol.  What am I missing?