@bitspook's personal website: Elisp - bitspook.inhttps://bitspook.in/tags/elisp/feed.xml2024-09-08T12:36:46.009783ZCharanjit Singhhttps://bitspook.in/images/avatar.pngExtending org-mode to handle youtube links/blog/extending-org-mode-to-handle-youtube-links/index.html2022-09-26T00:00:00.000000ZCharanjit Singh2022-09-26T00:00:00.000000Z<p> <iframe width="560" height="315" src="//youtube.com/embed/eaZUZCzaIgw" title="nil" frameborder="0" allowfullscreen=""></iframe> </p> <div id="outline-container-Requirement" class="outline-2"> <h2 id="Requirement">Requirement</h2> <div class="outline-text-2" id="text-Requirement"> <ol class="org-ol"> <li>I want to open youtube links in my notes in <code>mpv</code> instead of opening the
browser</li> <li>When exporting to HTML, youtube links should become embedded videos instead
of hyperlinks</li> </ol> </div> </div> <div id="outline-container-Implementation" class="outline-2"> <h2 id="Implementation">Implementation</h2> <div class="outline-text-2" id="text-Implementation"> <p> Org has a concept of 'link types'. We can add a new type of link and have it
behave the way we want. </p> <ul class="org-ul"> <li><p> <code>org-link-parameters</code> </p> <p> This variable contains link types and how they behave on follow (i.e when
someone opens the link with <code>C-c C-o</code>), export etc. A type of a link is
determined by the string before first ":" in it. e.g "<a href="https://bitspook.in">https://bitspook.in</a>" has <code>https</code> type, "<a href="file:///etc">file:///etc</a>" has <code>file</code> type. </p> <p> Items in this list has 2 main components: </p> <ol class="org-ol"> <li>First element is string representing the link type</li> <li>Key-value pairs of behavior name (e.g <code>:follow</code>, <code>:export</code>) and
function which handles that behavior</li> </ol> <p> For example: </p> <div class="org-src-container"> <pre class="src src-elisp">((<span style="color: #6aaf50;">"yt"</span> <span style="color: #7f7dca;">:follow</span> spook-org--follow-yt-link <span style="color: #7f7dca;">:export</span> spook-org--export-yt-link)
(<span style="color: #6aaf50;">"eww"</span> <span style="color: #7f7dca;">:follow</span> org-eww-open <span style="color: #7f7dca;">:store</span> org-eww-store-link))
</pre> </div></li> <li><p> <code>org-link-set-parameters</code> </p> <p> This function is used to add new link-types (and also to add new behavior to
existing ones). You can check the docs for <code>org-link-parameters</code> (with <code>C-h v
org-link-parameters</code>) to see arguments provided to each type of callback. </p></li> </ul> <p> Here's the code I've added in <a href="https://github.com/bitspook/spookmax.d">my emacs config</a>: </p> <div class="org-src-container"> <pre class="src src-elisp">(<span style="color: #598bc1;">defun</span> <span style="color: #1d9a79;">spook-org--follow-yt-link</span> (path prefix)
(<span style="color: #598bc1;">let*</span> ((url (format <span style="color: #6aaf50;">"https:%s"</span> path))
(proc-name (format <span style="color: #6aaf50;">"*yt://%s*"</span> url)))
(<span style="color: #598bc1;">if</span> (<span style="color: #598bc1;">and</span> prefix (executable-find <span style="color: #6aaf50;">"mpv"</span>))
(browse-url url)
(make-process <span style="color: #7f7dca;">:name</span> proc-name <span style="color: #7f7dca;">:buffer</span> proc-name <span style="color: #7f7dca;">:command</span> `(<span style="color: #6aaf50;">"mpv"</span> ,url))
(message <span style="color: #6aaf50;">"Launched mpv in buffer: %s"</span> proc-name))))
(<span style="color: #598bc1;">defun</span> <span style="color: #1d9a79;">spook-org--export-yt-link</span> (path desc backend)
(<span style="color: #598bc1;">when</span> (eq backend 'html)
(<span style="color: #598bc1;">let*</span> ((video-id (cadar (url-parse-query-string path)))
(url (<span style="color: #598bc1;">if</span> (string-empty-p video-id) path
(format <span style="color: #6aaf50;">"//youtube.com/embed/%s"</span> video-id))))
(format
<span style="color: #6aaf50;">"<iframe width=\"560\" height=\"315\" src=\"%s\" title=\"%s\" frameborder=\"0\" allowfullscreen></iframe>"</span>
url desc))))
(org-link-set-parameters <span style="color: #6aaf50;">"yt"</span> <span style="color: #7f7dca;">:follow</span> #'spook-org--follow-yt-link <span style="color: #7f7dca;">:export</span> #'spook-org--export-yt-link)
</pre> </div> <p> <code>make-process</code> will create a background buffer named <code>*yt://<url>*</code> which
allow monitoring and killing the mpv process. </p> <p> <i>Update</i>: Use <code>make-process</code> instead of <code>async-shell-command</code> for launching mpv.
Thanks to <a href="https://www.reddit.com/r/emacs/comments/xls0ih/extending_orgmode_to_handle_youtube_links/iplpk57/">nv-elisp on /r/emacs</a> </p> </div> </div> <div id="outline-container-Result" class="outline-2"> <h2 id="Result">Result</h2> <div class="outline-text-2" id="text-Result"> <ol class="org-ol"> <li><code>C-c C-o</code> (i.e <code>org-open-at-point</code>) on a <code>yt://</code> link opens the youtube video
in mpv</li> <li><code>C-u C-c C-o</code> (i.e <code>org-open-at-point</code> with an prefix argument) on a <code>yt://</code> link opens the video in browser</li> <li>When exported to HTML, all <code>yt://</code> links file are exported as embedded
youtube videos</li> </ol> </div> </div> <div id="outline-container-Bonus%20gains%20%F0%9F%92%AA" class="outline-2"> <h2 id="Bonus%20gains%20%F0%9F%92%AA">Bonus gains 💪</h2> <div class="outline-text-2" id="text-Bonus%20gains%20%F0%9F%92%AA"> <p> Recently I've been building a tool (<a href="https://github.com/bitspook/cl-ownpress">cl-ownpress</a>) which to make blogging a
zero-effort activity for me. Since I have already built a habit of judicious
note taking, publishing a subset of my notes will enable maintaining an active
blog without doing any "work". </p> <p> I've also been making thickly-accented-awkardly-narrated youtube videos. These
are almost always <i>tldr;</i> videos for my blog posts. So they get embedded in my
blog posts. </p> <p> 'Blog with notes + embed youtube videos' become easier to do with this little
tinkering. Since <a href="https://github.com/bitspook/cl-ownpress">cl-ownpress</a> uses my running Emacs to publish my posts, I don't
need to make any change in my blogging setup. I can embed my <i>tldr;</i> videos in
my blog posts by just prefixing youtube links with <code>yt://</code> instead of <code>https://</code>. </p> <p> I am pretty happy that I got zero work blogging-setup, and zero work
extending-the-blogging-setup as well. </p> </div> </div> Using ELisp as an HTML templating engine/blog/using-elisp-as-an/index.html2022-04-08T00:00:00.000000ZCharanjit Singh2022-04-08T00:00:00.000000Z<p> <iframe width="560" height="315" src="//www.youtube.com/embed/9Pcv5W1Gnvg" title="TLDR Video" frameborder="0" allowfullscreen=""></iframe> </p> <p> HTML templating engines like <a href="https://jinja.palletsprojects.com/en/3.1.x/">Jinja</a> or <a href="https://handlebarsjs.com/">handlebars</a> are commonly used in web
development for weaving data into HTML. </p> <p> For last couple of days, I've been porting <a href="https://github.com/bitspook/brandi">my Hakyll based static-site generator</a> to <a href="https://github.com/bitspook/press.el">Emacs Lisp</a>, for a more fluent thought-publishing workflow. I found myself in
need of an HTML templating engine so I could convert data about my blog posts
and notes to HTML. </p> <p> I found that we actually don't need an HTML templating engine to convert ELisp
to HTML. Emacs has built-in capability to work with HTML, we can piggy back on
that to get a templating engine without adding any new code. </p> <p> We can represent DOM, which is a tree data-structure, as a lisp form </p> <p> Consider following HTML element </p> <div class="org-src-container"> <pre class="src src-html"><<span style="color: #1d9a79;">div</span> <span style="color: #b6b635;">class</span>=<span style="color: #6aaf50;">"container"</span>>
<<span style="color: #1d9a79;">a</span> <span style="color: #b6b635;">href</span>=<span style="color: #6aaf50;">"https://google.com"</span>>Google</<span style="color: #1d9a79;">a</span>>
</<span style="color: #1d9a79;">div</span>>
</pre> </div> <p> We can write it as a lisp form like this: </p> <div class="org-src-container"> <pre class="src src-elisp">'(div ((class . <span style="color: #6aaf50;">"container"</span>))
(a ((href . <span style="color: #6aaf50;">"https://google.com"</span>))
<span style="color: #6aaf50;">"Google"</span>))
</pre> </div> <p> Note that this is a quoted lisp form. Which means this code isn't actually
executed, <code>div</code> or <code>a</code> aren't lisp functions. We can just put in any symbol
there, and it is treated as a DOM node. </p> <p> <code>shr-dom-to-xml</code> converts this lisp form to an HTML string: </p> <div class="org-src-container"> <pre class="src src-elisp">(<span style="color: #598bc1;">let</span> ((my-url <span style="color: #6aaf50;">"https://google.com"</span>))
(shr-dom-to-xml
`(div ((class . <span style="color: #6aaf50;">"container"</span>))
(a ((href . ,my-url))
<span style="color: #6aaf50;">"Google"</span>))))
</pre> </div> <pre class="example">
<div class="container"> <a href="https://google.com">Google</a></div>
</pre> <p> In this example we changed the quote used to showcase how we can run arbitrary
lisp forms in our DOM to weave data into it. </p> <p> You can check <a href="https://github.com/bitspook/press.el">my wip ELisp blogging setup</a> for more complex examples, and some
glue code I've written to make using ELisp as HTML templating engine easier. </p>