How to flexibly specify (no) closing tag?

[limist]

There are some (edge) cases where tags need to be self-closing, but are not known as such to hiccup's void-tags list. Modifying the void-tags would be inelegant. Is there a way to specify a tag as self-closing in a hiccup tag vector - especially as a local override of that tag's rendering to HTML/XML?

In particular, with sitemaps using the hreflang specification, per https://support.google.com/webmasters/answer/2620865?hl=en one can see that <xhtml:link ... /> tags are self-closing. If dealing with an isolated tag vector, it's possible to specify :mode xml to produce the desired outcome:

(require '[hiccup.core :as hic])

(hic/html [:xhtml:link (merge {:rel "alternate"} {:hreflang "en" :href http://www.foo.com/en"})])
;;=> "<xhtml:link href=\"http://www.foo.com/en\" hreflang=\"en\" rel=\"alternate\"></xhtml:link>"  INCORRECT, empty body and closing tag

(hic/html {:mode :xhtml} [:xhtml:link (merge {:rel "alternate"} {:hreflang "en" :href "http://www.foo.com/en"})])
;;=> "<xhtml:link href=\"http://www.foo.com/en\" hreflang=\"en\" rel=\"alternate\"></xhtml:link>"  INCORRECT, empty body and closing tag

(hic/html {:mode :xml} [:xhtml:link (merge {:rel "alternate"} {:hreflang "en" :href "http://www.foo.com/en"})])
;;=> "<xhtml:link href=\"http://www.foo.com/en\" hreflang=\"en\" rel=\"alternate\" />"  CORRECT

A problem arises when hic/html is being called on a larger collection of tag vectors, most of which render as desired, but we want some local overrides for the links of [:xhtml:link ...] See https://github.com/hashobject/sitemap and in particular https://github.com/hashobject/sitemap/blob/master/src/sitemap/core.clj

Any solutions/suggestions? Thanks!

[drakezhard]

I have the same problem but for the tag.

[Em-AK]

I don't understand when the problem arise here. But this Issue benefited me by documenting the :mode option 🙏