From 43ac54bcdc0e564e3df9772363ae80f1f0643cf8 Mon Sep 17 00:00:00 2001
From: Sacha Chua <sacha@sachachua.com>
Date: Sat, 27 Nov 2021 14:40:14 -0500
Subject: update

---
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@@ -0,0 +1,550 @@
+WEBVTT
+
+00:00.320 --> 00:00:03.679
+Hello all! Welcome to EmacsConf 2021.
+
+00:00:03.679 --> 00:00:05.040
+I'm Tom Gillespie.
+
+00:00:05.040 --> 00:00:06.799
+Thank you to the organizers for
+
+00:00:06.799 --> 00:00:07.680
+all your hard work,
+
+00:00:07.680 --> 00:00:08.639
+and for inviting me to
+
+00:00:08.639 --> 00:00:10.021
+give this short talk on
+
+00:00:10.021 --> 00:00:12.240
+"Org as an executable format".
+
+00:00:12.240 --> 00:00:13.840
+The links to the talk page,
+
+00:00:13.840 --> 00:00:16.000
+the GitHub page for the project,
+
+00:00:16.000 --> 00:00:18.880
+and the package on MELPA
+
+00:18.880 --> 00:00:20.160
+are listed on the right.
+
+00:00:20.160 --> 00:00:21.760
+Let's start with one of the motivating
+
+00:00:21.760 --> 00:00:25.920
+use cases for executable Org files.
+
+00:25.920 --> 00:00:29.339
+Many users keep global configuration
+
+00:00:29.339 --> 00:00:31.840
+for Org in an init.el file,
+
+00:00:31.840 --> 00:00:33.520
+which works for many workflows.
+
+00:00:33.520 --> 00:00:36.239
+However, for reproducible research,
+
+00:00:36.239 --> 00:00:37.600
+this is a challenge
+
+00:00:37.600 --> 00:00:39.280
+because if an Org file is
+
+00:00:39.280 --> 00:00:41.440
+dissociated from the init.el file,
+
+00:00:41.440 --> 00:00:43.040
+then often it will no longer
+
+00:00:43.040 --> 00:00:44.640
+function as expected.
+
+00:44.640 --> 00:46.719
+One potential solution to this problem
+
+00:46.719 --> 00:48.160
+is to be able to include all of the
+
+00:48.160 --> 00:00:50.239
+global configuration for Emacs
+
+00:00:50.239 --> 00:00:52.960
+and the environment in the Org file itself,
+
+00:00:52.960 --> 00:00:53.840
+in which case when you
+
+00:00:53.840 --> 00:00:55.440
+go to reuse the Org file,
+
+00:00:55.440 --> 00:00:58.640
+it will work as expected.
+
+00:58.640 --> 00:01:00.480
+What does an executable Org file
+
+00:01:00.480 --> 00:01:02.559
+look like in action?
+
+01:02.559 --> 01:05.280
+Here's a demo of an executable Org file
+
+01:05.280 --> 01:09.680
+running in Bash, Dash, Zsh, and PowerShell.
+
+01:09.680 --> 00:01:14.799
+So, we are currently in Bash,
+
+01:14.799 --> 01:19.360
+and we can run our demo,
+
+01:19.360 --> 00:01:21.119
+and it will print some stuff,
+
+00:01:21.119 --> 00:01:22.640
+and wait for input.
+
+01:22.640 --> 00:01:24.144
+We can also run it in Dash,
+
+00:01:24.144 --> 00:01:25.720
+which is the default for Debian
+
+00:01:25.720 --> 00:01:29.840
+and derivatives.
+
+01:29.840 --> 01:32.320
+Same program works as expected.
+
+01:32.320 --> 00:01:38.560
+Zsh also. And lastly PowerShell,
+
+01:38.560 --> 00:01:41.439
+if we try to run demo.org itself,
+
+00:01:41.439 --> 00:01:42.640
+we see (that) we get an error
+
+00:01:42.640 --> 00:01:43.764
+because PowerShell cares
+
+00:01:43.764 --> 00:01:45.439
+about file extensions,
+
+01:45.439 --> 00:01:49.840
+so, if we symlink to ps1,
+
+00:01:49.840 --> 00:01:51.680
+then it works as expected,
+
+00:01:51.680 --> 00:01:53.341
+and there are ways to alias this,
+
+00:01:53.341 --> 00:01:55.044
+so that you can run it as a program
+
+00:01:55.044 --> 00:01:58.640
+without the ps1 extension.
+
+01:58.640 --> 02:03.920
+So, how does this work?
+
+02:03.920 --> 00:02:05.759
+There are three components
+
+00:02:05.759 --> 00:02:07.352
+to an executable Org file
+
+00:02:07.352 --> 00:02:08.560
+that all need to be present
+
+00:02:08.560 --> 00:02:10.080
+in order for this to work.
+
+02:10.080 --> 02:11.920
+Starting from the top of the file,
+
+02:11.920 --> 02:14.239
+we have a shebang block.
+
+02:14.239 --> 00:02:16.640
+Next we have an Org Babel block
+
+00:02:16.640 --> 00:02:17.760
+written in Emacs Lisp,
+
+00:02:17.760 --> 00:02:20.000
+which is what we actually saw executing,
+
+00:02:20.000 --> 00:02:20.959
+and then there are some
+
+00:02:20.959 --> 00:02:23.520
+eval local variables or Elvs
+
+02:23.520 --> 02:25.200
+that are involved in making this
+
+02:25.200 --> 02:26.800
+actually executable.
+
+02:26.800 --> 02:29.760
+Let's start with the shebang block.
+
+02:29.760 --> 00:02:33.280
+Org syntax does not have support
+
+00:02:33.280 --> 00:02:34.959
+for shebang lines.
+
+02:34.959 --> 02:37.120
+However, it supports the shebang block.
+
+02:37.120 --> 02:39.440
+This is because Org comments, blocks,
+
+02:39.440 --> 00:02:41.760
+keywords, etc. that start with the
+
+00:02:41.760 --> 00:02:43.920
+sharp sign have the same syntax as
+
+00:02:43.920 --> 00:02:46.720
+comments in POSIX and PowerShell.
+
+02:46.720 --> 00:02:53.280
+This block is in fact valid
+
+02:53.280 --> 00:02:55.040
+Bash, Dash, Zsh, PowerShell,
+
+00:02:55.040 --> 00:02:57.280
+and maybe some other shells as well.
+
+02:57.280 --> 00:03:02.480
+In essence what it does is,
+
+03:02.480 --> 00:03:03.440
+perform some setup
+
+00:03:03.440 --> 00:03:06.080
+to avoid polluting standard output,
+
+00:03:06.080 --> 00:03:07.516
+and then it runs Emacs
+
+00:03:07.516 --> 00:03:08.959
+to load the file itself.
+
+00:03:08.959 --> 00:03:12.640
+The Elisp that is passed on the command line
+
+00:03:12.640 --> 00:03:14.959
+is explicated over here on the right,
+
+03:14.959 --> 00:03:17.920
+and in essence what it does is,
+
+00:03:17.920 --> 00:03:20.480
+to keep the startup time minimal
+
+00:03:20.480 --> 00:03:21.760
+and as low as possible,
+
+00:03:21.760 --> 00:03:24.080
+it loads the absolute bare minimum
+
+00:03:24.080 --> 00:03:25.120
+needed for Babel,
+
+00:03:25.120 --> 00:03:27.519
+and then it calls hack-local-variables
+
+00:03:27.519 --> 00:03:31.680
+triggering the eval-local-variables.
+
+03:31.680 --> 00:03:33.614
+What do the eval-local-variables do,
+
+00:03:33.614 --> 00:03:34.799
+and how those work?
+
+00:03:34.799 --> 00:03:36.319
+The essence of the approach is to
+
+00:03:36.319 --> 00:03:38.720
+use org-confirm-babel-evaluate
+
+00:03:38.720 --> 00:03:40.480
+to allow Babel execution.
+
+00:03:40.480 --> 00:03:43.360
+We can't set it to nil because that is
+
+00:03:43.360 --> 00:03:45.308
+an arbitrary code execution vector,
+
+00:03:45.308 --> 00:03:48.000
+which we don't want if we're sharing files.
+
+03:48.000 --> 00:03:49.555
+Instead what we do is,
+
+00:03:49.555 --> 00:03:52.000
+we use the fact that it can be a function,
+
+00:03:52.000 --> 00:03:55.280
+and we normalize the block of code,
+
+00:03:55.280 --> 00:03:57.320
+we checksum it, and then we check
+
+00:03:57.320 --> 00:03:59.280
+that it matches this checksum up here
+
+00:03:59.280 --> 00:04:00.400
+at the top of the file,
+
+00:04:00.400 --> 00:04:02.640
+and then sort of inside there,
+
+04:02.640 --> 00:04:04.159
+inside of org-sbe,
+
+00:04:04.159 --> 00:04:06.560
+which is Org source block evaluate,
+
+04:06.560 --> 04:08.959
+we call the block.
+
+04:08.959 --> 00:04:11.120
+The actual implementation of this
+
+00:04:11.120 --> 00:04:12.497
+is somewhat more complicated.
+
+00:04:12.497 --> 00:04:14.799
+However, it's small enough to fit in
+
+00:04:14.799 --> 00:04:17.519
+the local variables at the end of the file.
+
+04:17.519 --> 00:04:19.040
+One thing to note is that
+
+00:04:19.040 --> 00:04:20.799
+if you are using PowerShell,
+
+00:04:20.799 --> 00:04:23.919
+PowerShell parses the whole file
+
+00:04:23.919 --> 00:04:25.040
+which means that
+
+00:04:25.040 --> 00:04:27.759
+for any normal Org content,
+
+00:04:27.759 --> 00:04:28.639
+you need to put it in
+
+04:28.639 --> 00:04:30.240
+a multi-line PowerShell comment,
+
+00:04:30.240 --> 00:04:31.199
+and close it.
+
+00:04:31.199 --> 00:04:32.371
+So, once we hit
+
+00:04:32.371 --> 00:04:34.160
+hack-local-variables at the end,
+
+00:04:34.160 --> 00:04:37.120
+we run the eval-local-variables block,
+
+00:04:37.120 --> 00:04:40.880
+then we enter this Elisp block,
+
+04:40.880 --> 00:04:42.720
+and you can write whatever you want.
+
+00:04:42.720 --> 00:04:44.160
+All the power of Org Babel is
+
+00:04:44.160 --> 00:04:45.360
+now at your fingertips
+
+00:04:45.360 --> 00:04:47.199
+in order to do what you need
+
+04:47.199 --> 04:48.800
+for this file.
+
+04:48.800 --> 00:04:50.320
+Finally, let's do a quick demo
+
+00:04:50.320 --> 00:04:52.453
+of how to use this to make
+
+00:04:52.453 --> 00:04:54.800
+your own Org files executable.
+
+04:54.800 --> 00:05:01.840
+Orgstrap is available on MELPA as mentioned,
+
+05:01.840 --> 00:05:06.080
+and it can be installed using package.el
+
+00:05:06.080 --> 00:05:11.280
+by calling package-install orgstrap.
+
+05:11.280 --> 05:13.520
+It will download, and it will install.
+
+05:13.520 --> 00:05:18.720
+Then you can open an existing file
+
+05:18.720 --> 00:05:21.919
+or a new file. In this case,
+
+00:05:21.919 --> 00:05:25.199
+let me open a file called example.org.
+
+05:25.199 --> 00:05:26.996
+And then orgstrap provides
+
+00:05:26.996 --> 00:05:29.360
+command called orgstrap-init.
+
+05:29.360 --> 00:05:30.953
+What orgstrap-init does is,
+
+00:05:30.953 --> 00:05:33.759
+it populates a file with the machinery
+
+05:33.759 --> 00:05:36.639
+needed to run an orgstrap block.
+
+00:05:36.639 --> 00:05:38.560
+We're just going to do a message
+
+05:38.560 --> 05:43.440
+"hello orgstrap!".
+
+05:43.440 --> 00:05:46.160
+If you look up at the top,
+
+00:05:46.160 --> 00:05:47.386
+you will see that the
+
+00:05:47.386 --> 00:05:50.320
+orgstrap-block-checksum will change
+
+05:50.320 --> 00:05:51.520
+when I save the file.
+
+00:05:51.520 --> 00:05:53.840
+This makes it much easier to author files
+
+00:05:53.840 --> 00:05:55.120
+with orgstrap blocks.
+
+00:05:55.120 --> 00:05:56.560
+And then we need one last piece
+
+00:05:56.560 --> 00:05:57.876
+of machinery,
+
+00:05:57.876 --> 00:06:00.400
+which is the shebang block.
+
+00:06:00.400 --> 00:06:01.520
+I am just going to steal
+
+00:06:01.520 --> 00:06:02.560
+the shebang block from
+
+00:06:02.560 --> 00:06:06.080
+this other file over here
+
+06:06.080 --> 00:06:07.039
+since it is available.
+
+00:06:07.039 --> 00:06:08.880
+You can also get it from shebang.org,
+
+00:06:08.880 --> 00:06:10.800
+and I have plans to add a command
+
+00:06:10.800 --> 00:06:12.560
+to insert this into the file directly,
+
+00:06:12.560 --> 00:06:15.600
+which may actually be done by the time
+
+00:06:15.600 --> 00:06:19.520
+this video is actually posted and visible.
+
+06:19.520 --> 00:06:21.120
+There's one last step,
+
+00:06:21.120 --> 00:06:24.160
+which is that we need to run dired
+
+06:24.160 --> 00:06:27.520
+in order to… There we go.
+
+06:27.520 --> 06:31.039
+So, we use Shift m, capital m,
+
+06:31.039 --> 00:06:32.800
+in order to make our
+
+00:06:32.800 --> 00:06:35.520
+example file executable,
+
+06:35.520 --> 00:06:42.140
+and then if we come back to here,
+
+00:06:42.140 --> 00:06:47.360
+we see that example.org is now executable,
+
+00:06:47.360 --> 00:06:48.000
+and we can run it.
+
+06:48.000 --> 06:50.560
+"hello orgstrap!", and we're done.
+
+06:50.560 --> 06:52.639
+So, that's the basic workflow
+
+06:52.639 --> 06:54.880
+for getting orgstrap files
+
+06:54.880 --> 00:06:56.240
+to be executable.
+
+00:06:56.240 --> 00:06:58.960
+I will be around to answer questions live,
+
+00:06:58.960 --> 00:07:00.800
+and I will be also available in
+
+00:07:00.800 --> 00:07:03.280
+the #emacsconf IRC channel all day.
+
+00:07:03.280 --> 00:07:04.960
+I hope you have found this useful,
+
+00:07:04.960 --> 00:07:08.160
+and thank you very much for watching.
+
+00:07:08.160 --> 00:07:09.160
+[captions by bhavin192 (Bhavin Gandhi)]
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