Re: [PATCH] Fix numbering of captioned images

[Kyle Meyer]

Pablo Barraza Cornejo writes:

> When exporting to HTML, the exporter is supposed to check if there 
> are additional constraints over a paragraph using 
> `org-html-standalone-image-predicate'.  A misplaced quote causes 
> `org-html-standalone-image-p' to not apply them.

Thanks for catching the issue and for sending a patch.  This looks like
a regression introduced way back in 8.2.7 by ab1ce2a75 (ox-html: Fix
spurious "figure" divs on empty paragraphs, 2014-05-15).

> Subject: [PATCH] ox-html.el/inline-image export: Fix caption numbering.

The convention in this project is to leave off the trailing period from
the subject.

> * lisp/ox-html.el (org-html-standalone-image-p): Remove quote  which
> causes `org-html-standalone-image-p' to not check if 
> `org-html-standalone-image-predicate' is bound.

Please fill this line to ~70 characters (set in the repo's
.dir-locals.el).

>      (and (eq (org-element-type paragraph) 'paragraph)
> -      (or (not (fboundp 'org-html-standalone-image-predicate))
> +      (or (not (fboundp org-html-standalone-image-predicate))
>            (funcall org-html-standalone-image-predicate paragraph))

This quote will indeed result in the fboundp call always returning nil:

  (let ((org-html-standalone-image-predicate #'org-html--has-caption-p))
    (fboundp 'org-html-standalone-image-predicate))  ; => nil

  (let ((org-html-standalone-image-predicate #'org-html--has-caption-p))
    (fboundp org-html-standalone-image-predicate))   ; => t

However, the proposed change will introduce another issue.
org-html-standalone-image-predicate is defined as

  (defvar org-html-standalone-image-predicate)

That means it's left uninitialized:

  (defvar my/foo)   ; => my/foo
  (boundp 'my/foo)  ; => nil
  (fboundp my/foo)  ; error: (void-variable my/foo)

What about returning to the boundp/fboundp combination that was in place
before ab1ce2a75?

  (and (boundp 'my/foo)
       (fboundp my/foo))    ; => nil
  
  (let ((my/foo #'ignore))
    (and (boundp 'my/foo)
         (fboundp my/foo)))  ; => t