lexical binding changes symbol standard-value property

lexical binding changes symbol standard-value property

[Paul Rankin]

Something strange is going on with lexical-binding and defcustom...

(defcustom dummy-var t
  "This is a test var.")
;; => dummy-var

(car (get 'dummy-var 'standard-value))
;; => t

(setq lexical-binding t)
;; => t

(defcustom dummy-var t
  "This is a test var.")
;; = dummy-var

(car (get 'dummy-var 'standard-value))
;; => (funcall (function (closure (t) nil t)))

Why is the standard-value property of dummy-var changing? I kinda need it to be consistent...

I can resolve with:
(eval (car (get 'dummy-var 'standard-value)
;; => t
...but not sure about using (eval ...)

Ideas?

-- 
Paul W. Rankin
www.paulwrankin.com

RE: lexical binding changes symbol standard-value property

[Drew Adams]

> (car (get 'dummy-var 'standard-value))
> ;; => (funcall (function (closure (t) nil t)))
> 
> Why is the standard-value property of dummy-var changing? I kinda need it to
> be consistent...
> 
> I can resolve with:
> (eval (car (get 'dummy-var 'standard-value)
> ;; => t
> ...but not sure about using (eval ...)
> 
> Ideas?

Kinda looks like a bug, to me.

Re: lexical binding changes symbol standard-value property

[Stefan Monnier]

> (car (get 'dummy-var 'standard-value))
> ;; => t

(car (get 'dummy-var 'standard-value)) is defined to contain an
*expression* rather than a *value*.

> I can resolve with:
> (eval (car (get 'dummy-var 'standard-value)
> ;; => t
> ...but not sure about using (eval ...)

Using `eval' is (and always has been) the only correct way to get the
"standard-value".

E.g.

    (defcustom sm-test (+ 1 2) "hello")
    (car (get 'sm-test 'standard-value))

returns (+ 1 2) rather than 3 (well, with lexical-binding it returns
yet something else, but that is also an expression which evaluates to
3).


        Stefan