this post was submitted on 29 Oct 2023
3 points (100.0% liked)

Emacs

313 readers
3 users here now

A community for the timeless and infinitely powerful editor. Want to see what Emacs is capable of?!

Get Emacs

Rules

  1. Posts should be emacs related
  2. Be kind please
  3. Yes, we already know: Google results for "emacs" and "vi" link to each other. We good.

Emacs Resources

Emacs Tutorials

Useful Emacs configuration files and distributions

Quick pain-saver tip

founded 1 year ago
MODERATORS
 

Hi Emacs community,

I'm an elisp noob, and I recently wrote a function to get the references on a wikipedia page. I plan on using it for org-mode/org-roam so I can do research faster (even though there's probably already a package for that sort of thing). Unfortunately, it's probably not as robust as I would like to think it is, as some of the dois/isbns appear to be missing in some wikipedia pages I've tested. Here it is for reference:

(defun get-wikipedia-references (subject)
  "Gets references for a wikipedia article"
  (let ((wikipedia-prefix-url "https://en.wikipedia.org/wiki/"))
    (with-current-buffer
	(url-retrieve-synchronously (concat wikipedia-prefix-url subject))
      (let* ((html-start (progn (goto-char (point-min))
				(re-search-forward "^$")))
	     (dom (libxml-parse-html-region (1+ (point)) (point-max)))
	     (result))
	(dolist (cite-tag (dom-by-tag dom 'cite) result)
	  (let ((cite-class (dom-attr cite-tag 'class)))
	    (cond ((string-search "journal" cite-class)
		   (let ((a-tag (dom-search cite-tag (lambda (tag) (string-prefix-p "https://doi.org" (dom-attr tag 'href))))))
		     (setq result (cons (cons (concat "doi:" (dom-text a-tag))
					      (let* ((cite-texts (dom-texts cite-tag))
						     (title-beg (1+ (string-search "\"" cite-texts)))
						     (title-end (string-search "\"" cite-texts (1+ title-beg))))
						(substring cite-texts title-beg title-end)
						))
					result))))
		  ((string-search "book" cite-class)
		   (let ((a-tag (dom-search cite-tag (lambda (tag) (string-prefix-p "/wiki/Special:BookSources" (dom-attr tag 'href))))))
		     (setq result (cons (cons (concat "isbn:" (dom-text (dom-child-by-tag a-tag 'bdi)))
					      (dom-text (dom-child-by-tag cite-tag 'i)))
					result))))
		  (t
		   (let ((a-tag (assoc 'a cite-tag)))
		     (setq result (cons (cons (dom-attr a-tag 'href) (dom-text a-tag)) result))))
		  ))
	  )))))

(get-wikipedia-references "Graph_traversal")
(("doi:10.1109/SFCS.1979.34" . "Random walks, universal traversal sequences, and the complexity of maze problems")
 ("doi:10.1016/j.tcs.2015.11.017" . "Lower and upper competitive bounds for online directed graph exploration")
 ("doi:10.1016/j.tcs.2020.06.007" . "Online graph exploration on a restricted graph class: Optimal solutions for tadpole graphs")
 ("doi:10.1587/transinf.E92.D.1620" . "The Online Graph Exploration Problem on Restricted Graphs")
 ("doi:10.1016/j.tcs.2021.04.003" . "An improved lower bound for competitive graph exploration")
 ("doi:10.1137/0206041" . "An Analysis of Several Heuristics for the Traveling Salesman Problem"))

And yes, I know that I could probably use a library like s, dash, seq, or cl, but I try to keep my elisp functions free of those kind of things. I would appreciate any criticism from the Emacs community about my elisp!

you are viewing a single comment's thread
view the rest of the comments
[–] ElfOfPi@alien.top 1 points 1 year ago

I read a reddit post saying that using cl-lib was kind of a bad thing, and I think I've always had a fear that using libraries in my config would just make it more bloated/slow Emacs down. But after all the comments here, I think I'll change my stance on that.