Re: Should (boundp object) be tested and what would it mean

On 2026-04-12 22:33, Heime wrote:
> Have made this function This function to tell me the symbol name
> of the type of object being passed.
> 
> Should one test for (boundp object) and what would that mean exactly?
> 
> (defun lana-obnam (object)
>   "Return variable/symbol NAME holding OBJECT."
>   (cond
>     ((symbolp object)  (symbol-name object))
> 
>     ;;((boundp object)  (something))
> 
>     ((hash-table-p object)  "hash-table")
>     ((plistp object)        "plist")
> 
>     (t  (format "%s" object))))

- boundp tests whether a symbol has a value bound to it
- boundp expects a symbol as argument, not just any object.

(setq myvar 42) ⇒ 42     ;; Now myvar is bound
(boundp 'myvar) ⇒ t     ;; → t

(setq myvar nil) ⇒ nil    ;; Still bound (has value nil)
(boundp 'myvar) ⇒ t     ;; → t

(makunbound 'myvar) ⇒ myvar ;; Unbind it
(boundp 'myvar) ⇒ nil     ;; → nil

(defun lana-obnam (object)
   "Return description of OBJECT.
If OBJECT is a symbol, return its name.
If OBJECT is a bound symbol, also indicate it has a value.
Otherwise return the type or value as string."

   (cond
     ((symbolp object)
      (if (boundp object)
          (format "symbol '%s (value: %s)" object (symbol-value object))
        (format "symbol '%s (unbound)" object)))

     ((hash-table-p object)  "hash-table")
     ((plistp object)        "plist")
     (t  (format "%s" object))))

(setq myvar 1) ⇒ 1
(lana-obnam 'myvar) ⇒ "symbol 'myvar (value: 1)"   ;; Pass the SYMBOL 
myvar
(lana-obnam myvar) ⇒ "1"    ;; Pass the VALUE of myvar

-- 
Jean Louis