Re: [patch][ox-html] Support for level based containers

[Nicolas Goaziou <n.goaziou@gmail.com>]

Hello,

Rasmus <rasmus@gmx.us> writes:

> This patch allows different containers in ox-html.el depending on the
> level of the heading.  For example, it is possible to get a container
> structure like this (level . container):
>
> *   . section
> **  . article
> *** . div
>
> This is good for HTML5 at least, and I suspect also for ox-publish
> projects.  I don't know if this additional semantics is useful for
> "HTML4".

Thank you for the patch.

> Let me know if you find you'd be willing to merge something like this

I don't know enough HTML to have an opinion here.

> and what changes are necessary, if any.

Some comments follow.

> +(defcustom org-html-container-element '(("div" . "section")
> +					("div" . "article")
> +					("div" . "div"))
> +  "HTML elements to use for wrapping sections.
>  Can be set with the in-buffer HTML_CONTAINER property or for
>  publishing, with :html-container.
>  
> -Note that changing the default will prevent you from using
> -org-info.js for your website."
> +Should be a list of cons cells with positions corresponding to a

A "list of cons cells" is an "alist".

> +section.  If `org-html-html5-fancy' is t the cdr is used
> +otherwise the car.

"is non-nil" is better than "is t". Also, you shouldn't use
`org-html-html5-fancy': see below.

> +Note that changing the default will prevent you from
> +using org-info.js for your website."
>    :group 'org-export-html
>    :version "24.4"
>    :package-version '(Org . "8.0")
> -  :type 'string)
> +  :type '(repeat (cons string string)))

There is an `alist' type. See (info "(elisp) Composite Types")

> +      (let* ((hc (plist-get info :html-container))
> +	     (n (org-export-get-relative-level headline info)))

You don't need a starred `let' here. Also, I suggest to not use short
variable names. IMO "container-alist" is better than "hc" and "level"
better than "n".

> +	(cond ((listp hc)
> +	       (or (funcall (if org-html-html5-fancy 'cdr-safe 'car-safe)
> +			    (nth (1- (min n (length hc))) hc)) "div"))

You shouldn't use directly the variable `org-html-html5-fancy' since its
value can be overridden with external properties (e.g., during
a publishing process, with a specific setup). Instead, it should be:

  (plist-get info :html-html5-fancy)

As a rule of thumb, don't use variables when there's a property in INFO
for them.

Also, I don't think you need to use `car-safe' instead of `car' and
`cdr-safe' instead of `cdr'.

Eventually, due to the (min n (length hc)) (which should be documented
in the docstring) and the fact that the alist cannot be empty, the
`funcall' never evaluates to nil. Therefore, the `or' is not necessary.

> +	      ((and (stringp hc) (= 1 n))
> +	       (plist-get info :html-container))

Note that this branch is always false since HC shouldn't be a string,
per the defcustom type, but an alist.

> +	      (t "div")))))

Given the recommendations above, the whole `cond' could be rewritten:

  (funcall (if (plist-get info :html-html5-fancy) #'cdr #'car)
           (nth (1- (min level (length container-alist))) container-alist))


Regards,

-- 
Nicolas Goaziou