Re: eieio-base patch to support EDE project loading

[Stefan Monnier]

Hi Eric,

Thanks for the bug report and patch.  I'll look at it ASAP,


        Stefan


Eric Ludlam [2019-09-30 22:18:24] wrote:

> Hi,
>
> I've spent the last few years on emacs24, and just recently updated to newer
> version, and also attempted to switch to using built-in CEDET at the same
> time.  (I'd been using sourceforge version before.)  I am clearly a few
> years behind, hopefully you can forgive the transgression.
>
> In so doing, I discovered I couldn't load some of my old EDE projects.
> The error is in eieio-base.el (eieio-persistent-validate/fix-slot-value)
> with a call to `child-of-class-p' with a class being loaded that is 
> still an autoload.
>
> The core problem is in eieio-core.el (eieio-defclass-autoload).  There is
> a handy comment that explains it:
>
> ;; We used to store the list of superclasses in the `parent' slot (as a list
> ;; of class names).  But now this slot holds a list of class objects, and
> ;; those parents may not exist yet, so the corresponding class objects may
> ;; simply not exist yet.  So instead we just don't store the list of parents
> ;; here in eieio-defclass-autoload at all, since it seems that they're just
> ;; not needed before the class is actually loaded.
>
>
> Without that list of superclasses, `child-of-class-p' fails.  Since having
> the superclass list in autoloads is a non-starter, this patch will
> un-autoload classes found in the file being read before the call to
> `child-of-class-p'.
>
> It would be better to store the superclasses in the autoload declaration so
> that extensible class hierarchies can be more dynamically loaded without
> internal checks with un-autoload, but I don't know enough about how the new
> version of eieio works to provide that patch.
>
> I didn't extensively test this beyond a couple old EDE projects of mine.
>
> Hope this helps.
>
> Eric (original author of eieio from a few years back)
>
> -----
>
>
> diff --git a/lisp/emacs-lisp/eieio-base.el b/lisp/emacs-lisp/eieio-base.el
> index 534613811d..9131263761 100644
> --- a/lisp/emacs-lisp/eieio-base.el
> +++ b/lisp/emacs-lisp/eieio-base.el
> @@ -342,6 +342,10 @@ eieio-persistent-validate/fix-slot-value
>
>                 ;; We have a predicate, but it doesn't satisfy the predicate?
>                 (dolist (PV (cdr proposed-value))
> +                    ;; If PV is an autoload class, then we must load it
> before `child-of-class-p' will
> +                    ;; successfully detect what it is.
> +                    (eieio-class-un-autoload (car PV))
> +                    ;; Test the class found in the file
>                   (unless (child-of-class-p (car PV) (car classtype))
>                     (error "Invalid object: slot member %s does not match 
> class %s"
>                               (car PV) (car classtype))))