From e8e25c3c457b30b34bbae4c93ebd08ae48d1d710 Mon Sep 17 00:00:00 2001
From: Sacha Chua <sacha@sachachua.com>
Date: Mon, 29 Nov 2021 09:45:57 -0500
Subject: Update

---
 ...the-life-of-a-janitor--stefan-monnier--main.vtt | 1780 ++++++++++++++++++++
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diff --git a/2021/captions/emacsconf-2021-janitor--a-day-in-the-life-of-a-janitor--stefan-monnier--main.vtt b/2021/captions/emacsconf-2021-janitor--a-day-in-the-life-of-a-janitor--stefan-monnier--main.vtt
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+++ b/2021/captions/emacsconf-2021-janitor--a-day-in-the-life-of-a-janitor--stefan-monnier--main.vtt
@@ -0,0 +1,1780 @@
+WEBVTT
+
+00:01.520 --> 00:04.400
+Hello, my name is Stefan Monnier,
+
+00:04.400 --> 00:06.799
+and I'm going to talk to you about--
+
+00:06.799 --> 00:08.240
+well, I'm going to present a bit
+
+00:08.240 --> 00:11.840
+of the life of a janitor.
+
+00:11.840 --> 00:14.050
+So by and large, there's just
+
+00:14.050 --> 00:16.299
+nothing to see here,
+
+00:16.299 --> 00:17.199
+and that's probably
+
+00:17.199 --> 00:18.240
+not super interesting,
+
+00:18.240 --> 00:19.920
+but some of you might actually like to
+
+00:19.920 --> 00:00:23.050
+see how I work, so I figured why not.
+
+00:25.359 --> 00:27.279
+Usually what I do just doesn't make any
+
+00:27.279 --> 00:00:29.920
+any significant difference, 
+
+00:00:29.920 --> 00:00:32.160
+and so I basically take existing code
+
+00:00:32.160 --> 00:00:35.040
+that's working, and I try to change it
+
+00:00:35.040 --> 00:00:37.680
+hopefully without breaking it too much
+
+00:00:37.680 --> 00:00:40.079
+and make it slightly more...
+
+00:40.079 --> 00:42.719
+you know, following some of the more
+
+00:42.719 --> 00:44.640
+modern style, let's say,
+
+00:44.640 --> 00:00:46.719
+and sometimes along the way, 
+
+00:00:46.719 --> 00:00:50.399
+it actually fixes some bugs.
+
+00:50.399 --> 00:00:51.983
+More concretely, the kind of things 
+
+00:00:51.983 --> 00:00:54.079
+that I do is basically activate 
+
+00:00:54.079 --> 00:00:54.480
+lexical scoping--
+
+00:54.480 --> 00:56.239
+that's really my main goal usually--
+
+00:56.239 --> 00:58.960
+but also do things like convert
+
+00:58.960 --> 00:01:00.719
+from `cl` to `cl-lib`, 
+
+00:01:00.719 --> 00:01:01.440
+sometimes I have to
+
+01:01.440 --> 01:03.760
+fix some compilation dependencies,
+
+01:03.760 --> 01:07.280
+I might convert from `defadvice` to `advice-add`,
+
+01:07.280 --> 01:11.439
+and many of the things--
+
+01:11.439 --> 00:01:13.119
+in terms of number of changes, 
+
+00:01:13.119 --> 00:01:14.000
+most of them are actually 
+
+00:01:14.000 --> 00:01:16.560
+changing `quote fun` to `hash quote fun` 
+
+00:01:16.560 --> 00:01:17.360
+because I prefer it,
+
+01:17.360 --> 00:01:19.920
+but also it often helps me 
+
+00:01:19.920 --> 00:01:21.439
+have a better understanding 
+
+00:01:21.439 --> 00:01:23.920
+of which function is called where,
+
+01:23.920 --> 01:26.799
+and so the warnings I get from it
+
+01:26.799 --> 01:28.799
+sometimes help me.  You look concretely...
+
+01:28.799 --> 00:01:30.880
+it's not nothing really clear; 
+
+00:01:30.880 --> 00:01:33.360
+it's more in terms of helping me 
+
+00:01:33.360 --> 00:01:35.759
+have a mental image 
+
+00:01:35.759 --> 00:01:39.439
+of how the package works.
+
+01:39.439 --> 01:42.880
+So let's take a look.
+
+01:42.880 --> 00:01:45.840
+I'm going to start with 
+
+00:01:45.840 --> 00:01:46.799
+the package `heap`, 
+
+00:01:46.799 --> 00:01:50.560
+which I saw had a few weird things in it,
+
+00:01:50.560 --> 00:01:53.680
+so I'm going to compile it.
+
+01:53.680 --> 01:55.600
+That's basically the way the way I work,
+
+01:55.600 --> 00:01:57.840
+right. I take a package. 
+
+00:01:57.840 --> 00:02:00.479
+I just pass it to the byte compiler.  
+
+00:02:00.479 --> 00:02:02.159
+I do that by just having
+
+02:02.159 --> 02:04.560
+a clone of the whole
+
+02:04.560 --> 00:02:06.799
+GNU ELPA repository, 
+
+00:02:06.799 --> 00:02:10.000
+and so that's why I built them.
+
+02:10.000 --> 02:11.520
+I use the build rules 
+
+02:11.520 --> 02:15.120
+from the GNU ELPA repository.
+
+02:15.120 --> 00:02:16.720
+These build rules enforce-- 
+
+00:02:16.720 --> 00:02:17.680
+make sure that the files 
+
+00:02:17.680 --> 00:02:19.680
+are compiled in a clean environment 
+
+00:02:19.680 --> 00:02:21.920
+so you get fairly good warnings.  
+
+00:02:21.920 --> 00:02:23.680
+If you look at the warnings you see here, 
+
+00:02:23.680 --> 00:02:24.720
+there's a lot of things 
+
+00:02:24.720 --> 00:02:26.480
+which are completely irrelevant, 
+
+00:02:26.480 --> 00:02:28.400
+which are due to details 
+
+00:02:28.400 --> 00:02:30.319
+of the way I have my Emacs set up
+
+00:02:30.319 --> 00:02:31.599
+and some of the local changes 
+
+00:02:31.599 --> 00:02:34.319
+I had in it so, you know, 
+
+00:02:34.319 --> 00:02:35.280
+there's no point 
+
+00:02:35.280 --> 00:02:37.920
+paying too much attention to it,
+
+02:37.920 --> 02:40.400
+but here we have a first warning.
+
+02:40.400 --> 02:42.959
+We see that this is using `cl`,
+
+02:42.959 --> 02:45.040
+so we want to change this to `cl-lib`,
+
+02:45.040 --> 00:02:46.879
+but that also means 
+
+00:02:46.879 --> 00:02:48.400
+that we may have a new dependency 
+
+00:02:48.400 --> 00:02:49.920
+on the `cl-lib` package, 
+
+00:02:49.920 --> 00:02:51.120
+so we have to go check 
+
+00:02:51.120 --> 00:02:52.000
+the start of the file 
+
+00:02:52.000 --> 00:02:54.080
+to see if it already declares
+
+00:02:54.080 --> 00:02:56.800
+some dependency, and we see it doesn't,
+
+02:56.800 --> 00:03:00.640
+not even on a on a recent-enough Emacs,
+
+00:03:00.640 --> 00:03:02.325
+so we have to add-- 
+
+00:03:02.325 --> 00:03:05.360
+sorry, that's not going very well...
+
+03:05.360 --> 03:06.480
+oh...
+
+03:06.480 --> 03:08.560
+okay, we're going to get there somewhere...
+
+03:08.560 --> 03:13.200
+somehow...
+
+03:13.200 --> 03:18.020
+oh, that still wasn't it, wow, okay--
+
+03:20.480 --> 03:22.159
+and along the way...
+
+03:22.159 --> 00:03:24.159
+Of course, since we converted to `cl-lib`, 
+
+00:03:24.159 --> 00:03:26.159
+we have to update the uses
+
+00:03:26.159 --> 00:03:29.840
+so `defstruct` shouldn't be used anymore.
+
+03:29.840 --> 03:31.599
+We may want to reindent this
+
+03:31.599 --> 03:36.000
+to get something a bit cleaner.
+
+03:37.040 --> 00:03:40.589
+We have here a missing quote... 
+
+00:03:40.589 --> 00:03:41.920
+hash, sorry.
+
+03:41.920 --> 00:03:46.480
+We have `decf`, so `decf` is here,
+
+03:46.480 --> 00:03:48.000
+and that needs to be replaced 
+
+00:03:48.000 --> 00:03:49.920
+with `cl-decf`. 
+
+00:03:49.920 --> 00:03:51.120
+Sometimes it's worth doing 
+
+00:03:51.120 --> 00:03:53.360
+a search-and-replace.  
+
+00:03:53.360 --> 00:03:54.799
+Here I see there's only two,
+
+00:03:54.799 --> 00:03:57.760
+so it's not worth the trouble;
+
+03:57.760 --> 00:04:00.711
+I just do it by hand, and that's it.  
+
+00:04:00.711 --> 00:04:02.000
+Well, that was easy.
+
+04:02.000 --> 04:05.000
+So let's recompile, see what it says.
+
+04:10.159 --> 04:12.959
+Ah, this is clean.  Perfect!
+
+04:12.959 --> 04:15.000
+Let's.. we can go see...
+
+04:15.000 --> 04:17.280
+There is another one I had.
+
+04:17.280 --> 04:20.239
+Was it `counsel`, I think.  Yes.
+
+04:20.239 --> 00:04:24.160
+So also I saw some funny things
+
+00:04:24.160 --> 00:04:24.320
+going on here.
+
+04:24.320 --> 00:04:26.479
+So I'm going to do 
+
+00:04:26.479 --> 00:04:31.040
+the same procedure as before: 
+
+00:04:31.040 --> 00:04:32.800
+I just compile the file
+
+00:04:32.800 --> 00:04:35.000
+and look at the warnings.
+
+04:38.000 --> 04:40.479
+Oh, we have many more here.
+
+04:40.479 --> 04:43.120
+So let's see...
+
+04:43.120 --> 00:04:46.504
+Okay, so we have missing quotes-- 
+
+00:04:46.504 --> 00:04:49.240
+oh, hashes. They're not really missing;
+
+04:49.240 --> 04:54.639
+it's just a personal preference.
+
+04:54.639 --> 04:57.440
+Oh, here... here's an important one:
+
+04:57.440 --> 04:59.280
+so as you know,
+
+04:59.280 --> 05:00.639
+if you look at the top of the file,
+
+05:00.639 --> 00:05:02.240
+you see that here 
+
+00:05:02.240 --> 00:05:04.960
+it says it's using lexical binding,
+
+05:04.960 --> 05:07.120
+yet it's not fully using lexical binding,
+
+05:07.120 --> 00:05:08.960
+because as we just saw, 
+
+00:05:08.960 --> 00:05:11.039
+there's a call to the `eval` function 
+
+00:05:11.039 --> 00:05:11.680
+with only one argument,
+
+05:11.680 --> 05:13.280
+which means the second argument is nil,
+
+05:13.280 --> 05:16.880
+which means that the expression read
+
+05:16.880 --> 00:05:19.520
+by `read` here is going to be evaluated
+
+05:19.520 --> 00:05:22.160
+using the old dialects, 
+
+00:05:22.160 --> 00:05:24.240
+which is only dynamic scoping.  
+
+00:05:24.240 --> 00:05:25.680
+So here I like to just change this
+
+00:05:25.680 --> 00:05:26.800
+to use lexical scoping,
+
+05:26.800 --> 00:05:28.080
+which in most cases 
+
+00:05:28.080 --> 00:05:29.680
+just doesn't make any difference.
+
+00:05:29.680 --> 00:05:30.870
+It just makes me feel better.
+
+05:35.919 --> 05:40.160
+So there's lots of those hashes
+
+05:40.160 --> 05:41.759
+all over the place.
+
+05:43.680 --> 05:45.680
+It's not strictly necessary, as you know,
+
+05:45.680 --> 05:51.500
+but I'm just going to add them anyway.
+
+05:52.479 --> 00:05:53.199
+Here we see 
+
+00:05:53.199 --> 00:05:54.800
+it's not going to warn me here
+
+00:05:54.800 --> 00:05:55.759
+because it doesn't know 
+
+00:05:55.759 --> 00:05:57.600
+that `ivy-make-magic-action` 
+
+00:05:57.600 --> 00:05:58.400
+takes a function, 
+
+00:05:58.400 --> 00:06:02.319
+but it's a pretty good guess that it does.
+
+06:12.319 --> 06:14.479
+And here's some more.
+
+06:14.479 --> 06:16.080
+What else do we have?
+
+06:16.080 --> 06:19.120
+Is that all we have here?
+
+06:19.120 --> 06:21.440
+Well, looks like it.  Oh, I see a few...
+
+06:21.440 --> 06:27.680
+a few more here...
+
+06:27.680 --> 06:30.639
+and one more.
+
+06:30.639 --> 06:33.039
+And oh, this is more interesting.
+
+06:33.039 --> 06:35.280
+So here we have a use of `defadvice`,
+
+06:35.280 --> 06:37.440
+so if we go back
+
+06:37.440 --> 06:38.479
+to the beginning of the file,
+
+06:40.720 --> 06:42.880
+we see that it actually depends
+
+06:42.880 --> 00:06:47.360
+on Emacs 24.5, so it actually has
+
+06:47.360 --> 00:06:49.280
+the new advice system available 
+
+00:06:49.280 --> 00:06:51.520
+without having to add any dependency, 
+
+00:06:51.520 --> 00:06:53.599
+so there's really no good reason 
+
+00:06:53.599 --> 00:06:54.880
+to keep this.
+
+06:54.880 --> 00:06:56.160
+So we just convert this 
+
+00:06:56.160 --> 00:06:58.560
+to an `advice-add`,
+
+06:58.560 --> 00:06:59.840
+so it just says, you know, 
+
+00:06:59.840 --> 00:07:02.319
+this is the function that's advised.
+
+07:02.319 --> 07:04.560
+This was a `before` advice.
+
+07:04.560 --> 07:05.500
+The `before` advice, sometimes,
+
+07:05.500 --> 07:08.479
+when we convert it to `advice-add`,
+
+07:08.479 --> 07:11.199
+need to be converted to `around` advice.
+
+07:11.199 --> 07:13.280
+This is when the function
+
+07:13.280 --> 07:15.840
+looks or modifies the argument.
+
+07:15.840 --> 07:18.639
+In this case, if I look at it,
+
+07:18.639 --> 07:20.319
+I see it doesn't seem to be using
+
+07:20.319 --> 07:21.280
+the arguments at all.
+
+07:21.280 --> 00:07:25.280
+So I'm just going to keep it
+
+00:07:25.280 --> 00:07:27.520
+as a `before` advice.
+
+07:27.520 --> 00:07:28.672
+And we have to give it a name.
+
+00:07:28.672 --> 00:07:30.880
+Well, we don't really have to,
+
+07:30.880 --> 07:32.800
+but it's convenient to give it a name
+
+07:32.800 --> 07:34.800
+to the new function.
+
+07:34.800 --> 00:07:36.880
+So here, they actually had 
+
+00:07:36.880 --> 00:07:38.080
+given a name to the advice, 
+
+00:07:38.080 --> 00:07:39.599
+so we're going to keep it, 
+
+00:07:39.599 --> 00:07:41.440
+and indeed it's the only function.
+
+00:07:41.440 --> 00:07:43.360
+This name is not used as a function,
+
+00:07:43.360 --> 00:07:44.160
+so we can use it 
+
+00:07:44.160 --> 00:07:46.960
+as the name of the function.
+
+07:46.960 --> 00:07:49.039
+I'm going to add a dash here 
+
+00:07:49.039 --> 00:07:51.120
+because I think this function 
+
+00:07:51.120 --> 00:07:53.039
+is really fundamentally 
+
+00:07:53.039 --> 00:07:54.639
+an internal function.
+
+07:54.639 --> 07:56.720
+So here I just said I add the advice,
+
+07:56.720 --> 07:58.000
+but I still need to actually
+
+07:58.000 --> 07:59.800
+define the function.
+
+08:02.879 --> 00:08:04.160
+So that's what I do here, 
+
+00:08:04.160 --> 00:08:06.500
+and we need here to list the arguments
+
+08:06.500 --> 08:08.240
+that are going to be taken.
+
+08:08.240 --> 00:08:09.199
+I don't know what these are, 
+
+00:08:09.199 --> 00:08:10.960
+but I know we're not using them, 
+
+00:08:10.960 --> 00:08:13.759
+so we'll just accept anything,
+
+08:13.759 --> 08:16.560
+and that will do the trick.
+
+08:16.560 --> 08:19.199
+It's a future-proof as well,
+
+08:19.199 --> 08:22.240
+so that should work.
+
+08:22.240 --> 00:08:24.160
+Oh, here we have another, so it's 
+
+00:08:24.160 --> 00:08:29.919
+basically the same story, I think.
+
+08:29.919 --> 00:08:31.599
+It's a `before` advice as well.  
+
+00:08:31.599 --> 00:08:32.959
+It doesn't seem to be using
+
+00:08:32.959 --> 00:08:35.599
+the argument at all,
+
+08:35.599 --> 00:08:38.596
+and let's see if this name is not taken.
+
+00:08:38.596 --> 00:08:43.360
+Yeah, good, so we can just do the same:
+
+08:43.360 --> 08:46.880
+turn this into an `advice-add`...
+
+08:46.880 --> 08:48.300
+`before`...
+
+08:53.040 --> 08:55.000
+I just add a dash here.
+
+09:02.480 --> 00:09:05.440
+And same thing-- 
+
+00:09:05.440 --> 00:09:06.959
+a function that just takes...
+
+09:06.959 --> 09:08.240
+because I don't know which arguments
+
+09:08.240 --> 09:10.480
+these are so...
+
+09:10.480 --> 09:14.640
+I think that should do the trick.
+
+09:14.640 --> 00:09:16.080
+Actually, we see that this function 
+
+00:09:16.080 --> 00:09:18.560
+is very similar to the other one.
+
+09:18.560 --> 09:23.000
+Let's look at the two side-by-side...
+
+09:31.519 --> 00:09:33.055
+...it really is-- 
+
+00:09:33.055 --> 00:09:36.097
+oh, it's not exactly identical... 
+
+00:09:36.097 --> 00:09:39.120
+it's, you know, we could try
+
+09:39.120 --> 09:41.680
+to merge them into a single function,
+
+09:41.680 --> 09:43.279
+but it's probably not worth the trouble
+
+09:43.279 --> 09:45.920
+so we can keep it this way.
+
+09:45.920 --> 09:48.720
+Okay, next warning: an `eval` again,
+
+09:48.720 --> 09:50.640
+so I could just add `t` here,
+
+09:50.640 --> 00:09:55.120
+but if you look at it a bit more, 
+
+00:09:55.120 --> 00:09:56.000
+you see that the code 
+
+00:09:56.000 --> 00:09:57.760
+we're going to evaluate
+
+09:57.760 --> 00:09:59.279
+using either lexical scoping 
+
+00:09:59.279 --> 00:10:00.560
+or dynamic scoping 
+
+00:10:00.560 --> 00:10:03.440
+is actually just evaluating a symbol,
+
+00:10:03.440 --> 00:10:06.240
+since we just call an `intern` here.
+
+10:06.240 --> 00:10:07.839
+So instead of replacing this 
+
+00:10:07.839 --> 00:10:09.279
+by adding an argument, 
+
+00:10:09.279 --> 00:10:11.680
+I'm just going to call `symbol-value` 
+
+00:10:11.680 --> 00:10:12.640
+because that's exactly 
+
+00:10:12.640 --> 00:10:14.480
+what we need to do here, right.  
+
+00:10:14.480 --> 00:10:16.320
+I call this "strength reduction," 
+
+00:10:16.320 --> 00:10:17.200
+and I'm using 
+
+00:10:17.200 --> 00:10:19.680
+a more primitive function instead, 
+
+00:10:19.680 --> 00:10:23.200
+which does just what we need,
+
+10:23.200 --> 10:25.680
+and this one knows that it has to be
+
+10:25.680 --> 00:10:30.640
+accessed by dynamic scoping, of course.
+
+10:30.640 --> 00:10:32.959
+Here I have a `kmacro-ring`, 
+
+00:10:32.959 --> 00:10:35.600
+so here I have a function that uses--
+
+10:35.600 --> 00:10:37.360
+`kmacro-ring` comes from
+
+00:10:37.360 --> 00:10:39.760
+the `kmacro` package, obviously,
+
+10:39.760 --> 10:41.600
+and we probably don't want to
+
+10:41.600 --> 10:42.959
+`require` `kmacro` package
+
+10:42.959 --> 00:10:48.560
+all over the place in `counsel` itself,
+
+10:48.560 --> 00:10:50.240
+because `counsel` can be used 
+
+00:10:50.240 --> 00:10:53.279
+without `kmacro`.
+
+10:53.279 --> 00:10:55.200
+So I think we're just going to add 
+
+00:10:55.200 --> 00:11:04.000
+a `defvar` to silence the warning.
+
+11:05.519 --> 00:11:10.720
+And we have several more. So we have
+
+11:10.720 --> 00:11:14.000
+`initial-counter-value`. (Sorry.)
+
+11:20.480 --> 11:23.360
+We have `kmacro-counter`.
+
+11:23.360 --> 11:25.760
+Do we have more?
+
+11:25.760 --> 11:28.560
+Oh, yes, we do.
+
+11:28.560 --> 11:35.040
+We have `kmacro-counter-value-start`
+
+11:35.040 --> 11:40.839
+and `kmacro-counter-format-start`.
+
+11:40.839 --> 11:43.920
+Okay.
+
+11:45.040 --> 11:50.160
+I hope this is it.
+
+11:50.160 --> 11:52.880
+`kmacro-ring`, `counter`, `ring`...
+
+11:52.880 --> 11:54.959
+blah blah blah.
+
+11:54.959 --> 00:12:00.240
+Here we have another one, `quote`.
+
+12:00.240 --> 12:03.279
+Here we have another hash missing.
+
+12:03.279 --> 12:06.079
+It's not missing...
+
+12:06.079 --> 12:08.000
+but same thing here.
+
+12:12.079 --> 00:12:16.560
+Okay, this is a function from `kmacro`.
+
+12:16.560 --> 00:12:18.079
+We could declare it 
+
+00:12:18.079 --> 00:12:20.880
+just to silence the warning
+
+12:20.880 --> 00:12:22.320
+although we don't actually... 
+
+00:12:22.320 --> 00:12:24.480
+normally, when we declare such things--
+
+12:24.480 --> 00:12:25.279
+same thing with variables-- 
+
+00:12:25.279 --> 00:12:27.300
+we should try to make sure that indeed
+
+12:27.300 --> 12:28.760
+by the time the code is executed,
+
+12:28.760 --> 12:30.800
+the function will be available,
+
+12:30.800 --> 00:12:32.800
+and then very often is 
+
+00:12:32.800 --> 00:12:34.320
+because there's a `require` 
+
+00:12:34.320 --> 00:12:35.680
+sometimes inside a function, 
+
+00:12:35.680 --> 00:12:36.399
+and so we should put 
+
+00:12:36.399 --> 00:12:37.680
+the `declare` function 
+
+00:12:37.680 --> 00:12:39.920
+right after the `require`, 
+
+00:12:39.920 --> 00:12:41.839
+but I don't think it's the case here.
+
+12:41.839 --> 00:12:46.399
+So I'm just going to to add this.
+
+12:46.399 --> 12:49.040
+I know this comes from `kmacro`,
+
+12:49.040 --> 00:12:53.500
+and I could actually check the arguments.
+
+12:56.320 --> 00:12:58.480
+It's just taking an optional argument 
+
+00:12:58.480 --> 00:13:00.880
+so I'm going to put it there, 
+
+00:13:00.880 --> 00:13:06.720
+so we have it complete.
+
+13:06.720 --> 13:10.800
+Okay, we can just recompile,
+
+13:10.800 --> 00:13:14.800
+see what is left 
+
+00:13:14.800 --> 00:13:17.760
+from those warnings we've fixed, 
+
+00:13:17.760 --> 00:13:21.360
+and we may have new warnings, in any case, 
+
+00:13:21.360 --> 00:13:25.440
+because especially when we add the hashes,
+
+00:13:25.440 --> 00:13:29.519
+it tends to give us more warnings.
+
+13:29.519 --> 00:13:31.200
+So we have two more functions 
+
+00:13:31.200 --> 00:13:34.560
+which are not known.
+
+13:34.560 --> 13:39.440
+You can just add them here...
+
+13:39.440 --> 13:44.720
+`set-format "kmacro"`
+
+13:44.720 --> 13:48.160
+and same thing for `set-counter`.
+
+13:48.160 --> 13:50.000
+Okay, whatever.
+
+13:54.959 --> 00:13:57.120
+This just takes a `format` argument, 
+
+00:13:57.120 --> 00:14:05.920
+and this one just takes an `arg` argument.
+
+14:05.920 --> 14:10.800
+Okay, so let's see what this says now.
+
+14:10.800 --> 14:15.519
+Hopefully, there's no warnings anymore.
+
+14:15.519 --> 14:17.839
+We're done.  Okay!
+
+14:17.839 --> 00:14:20.079
+Okay, the last one we're going to see 
+
+00:14:20.079 --> 00:14:23.440
+is in `enwc`, I saw the other day...
+
+14:23.440 --> 14:26.240
+I think I have it here...
+
+14:27.760 --> 14:29.680
+here we go, yes...
+
+14:29.680 --> 14:32.800
+so `enwc` is an interesting package here
+
+14:32.800 --> 14:35.680
+because it has-- as you can see it has--
+
+14:35.680 --> 14:37.760
+it's lexical binding,
+
+14:37.760 --> 14:39.760
+but actually some of the files in it
+
+14:39.760 --> 14:42.320
+do not use lexical binding,
+
+14:42.320 --> 14:44.320
+so it has been partly converted
+
+14:44.320 --> 14:46.160
+but not completely.
+
+14:46.160 --> 00:14:49.920
+So here I'm going to 
+
+00:14:49.920 --> 00:14:54.160
+enable lexical binding.
+
+14:54.160 --> 14:58.880
+I have also, I think, in `cm`...
+
+14:58.880 --> 15:01.199
+yes...
+
+15:01.199 --> 15:04.000
+so I enable it here,
+
+15:04.000 --> 15:07.360
+and also, I think, `test`.
+
+15:07.360 --> 00:15:09.360
+The test files are often 
+
+00:15:09.360 --> 00:15:11.839
+somewhat problematic 
+
+00:15:11.839 --> 00:15:15.199
+because very often they're not quite
+
+15:15.199 --> 15:18.880
+as heavily tested themselves, actually,
+
+15:18.880 --> 00:15:20.320
+or they only run 
+
+00:15:20.320 --> 00:15:22.160
+in very specific contexts, 
+
+00:15:22.160 --> 00:15:24.399
+and so they may have problems 
+
+00:15:24.399 --> 00:15:27.360
+with missing `requires` or using packages 
+
+00:15:27.360 --> 00:15:29.199
+which are not explicitly in the dependencies
+
+15:29.199 --> 15:31.279
+and those kinds of things.
+
+15:31.279 --> 15:33.360
+I think this is not the case here,
+
+15:33.360 --> 15:35.440
+but we'll see.
+
+15:35.440 --> 15:38.880
+`enwc`...
+
+15:38.880 --> 15:42.320
+Yes, I want to save this one and that one.
+
+15:42.320 --> 15:45.000
+Let's see what it says.
+
+15:47.199 --> 15:51.440
+Okay, unused lexical variable `x`...
+
+15:51.440 --> 15:52.240
+`x`...
+
+15:52.240 --> 15:57.120
+Yes, so here we have an unused variable,
+
+15:57.120 --> 15:58.320
+and indeed, it's not used.
+
+15:58.320 --> 16:00.880
+It probably had to be named before
+
+16:00.880 --> 16:04.079
+because it was...
+
+16:04.079 --> 00:16:05.120
+with dynamic scoping, 
+
+00:16:05.120 --> 00:16:06.399
+the `dotimes` requires 
+
+00:16:06.399 --> 00:16:08.160
+the variable to be named, actually, 
+
+00:16:08.160 --> 00:16:10.399
+because it's used internally somehow,
+
+16:10.399 --> 00:16:11.600
+but with lexical scoping, 
+
+00:16:11.600 --> 00:16:12.320
+that's not the case,
+
+00:16:12.320 --> 00:16:14.079
+so we can just put an underscore.
+
+16:14.079 --> 00:16:15.199
+I'm going to change this 
+
+00:16:15.199 --> 00:16:16.880
+because I really don't like
+
+16:16.880 --> 16:19.000
+this three-part `dotimes`.
+
+16:19.000 --> 00:16:21.360
+I prefer to have 
+
+00:16:21.360 --> 00:16:23.040
+the return value at the end.
+
+16:23.040 --> 00:16:26.480
+It's sort of stashed hidden in the middle.
+
+16:26.480 --> 16:29.680
+That's just a personal preference.
+
+16:29.680 --> 16:31.920
+Okay, what else... we have a `widget`.
+
+16:31.920 --> 16:34.000
+Okay, this argument here says that
+
+16:34.000 --> 16:37.000
+it's not used, so if we look at...
+
+16:44.320 --> 00:16:47.040
+We were here, right?  Yes. Right here.  
+
+00:16:47.040 --> 00:16:50.480
+Indeed, `widget` is really not used.
+
+16:50.480 --> 16:51.230
+(Sorry.)
+
+16:53.600 --> 00:16:55.279
+Here's what I get for using 
+
+00:16:55.279 --> 00:16:58.320
+a somewhat vanilla configuration of Emacs,
+
+16:58.320 --> 17:01.279
+compared to the one I use...
+
+17:01.279 --> 17:04.000
+the personally tricked one.
+
+17:04.000 --> 17:05.439
+Actually, I can...
+
+17:05.439 --> 17:07.919
+so we can just mark this argument
+
+17:07.919 --> 17:09.360
+as unused,
+
+17:09.360 --> 17:11.199
+and we don't want to remove the argument
+
+17:11.199 --> 00:17:12.480
+probably, or maybe we could; 
+
+00:17:12.480 --> 00:17:15.679
+we could see where the function is used,
+
+17:15.679 --> 00:17:18.542
+and here we see that it's passed
+
+00:17:18.542 --> 00:17:20.959
+to a higher-order function,
+
+17:20.959 --> 17:24.480
+basically, so it's going to be...
+
+17:24.480 --> 00:17:25.360
+We can't really change 
+
+00:17:25.360 --> 00:17:25.760
+the calling convention
+
+17:25.760 --> 17:27.120
+so we have to mark the argument
+
+17:27.120 --> 17:29.600
+as being just an unused argument,
+
+17:29.600 --> 17:34.000
+but we're going to still receive it.
+
+17:34.000 --> 00:17:35.360
+And here it says same thing: 
+
+00:17:35.360 --> 00:17:38.240
+that `widget` is not used in this function.
+
+17:38.240 --> 17:40.000
+Let's take a look at the function.
+
+17:40.000 --> 17:42.400
+Indeed it seems it's not used,
+
+17:42.400 --> 17:44.000
+and so we're just going to mark it
+
+17:44.000 --> 17:46.480
+as unused.
+
+17:46.480 --> 00:17:48.320
+This is the part of the conversion
+
+00:17:48.320 --> 00:17:49.200
+to lexical scoping
+
+00:17:49.200 --> 00:17:51.280
+that's somewhat tricky sometimes
+
+00:17:51.280 --> 00:17:53.760
+because we don't really know 
+
+00:17:53.760 --> 00:17:56.240
+whether this variable should be using
+
+00:17:56.240 --> 00:17:58.559
+lexical scoping or dynamic scoping.
+
+17:58.559 --> 00:18:00.480
+The fact that it's not used 
+
+00:18:00.480 --> 00:18:02.320
+is a hint that there's probably 
+
+00:18:02.320 --> 00:18:03.679
+something going on,
+
+18:03.679 --> 00:18:04.960
+so either it's not used 
+
+00:18:04.960 --> 00:18:06.400
+because it should be using 
+
+00:18:06.400 --> 00:18:07.200
+dynamic scoping-- 
+
+00:18:07.200 --> 00:18:08.080
+it is going to be used 
+
+00:18:08.080 --> 00:18:10.480
+by some other code somewhere else--
+
+18:10.480 --> 00:18:11.840
+or it's really not used
+
+00:18:11.840 --> 00:18:14.000
+because it's just not used, right,
+
+00:18:14.000 --> 00:18:16.320
+and so we need to distinguish the two, 
+
+00:18:16.320 --> 00:18:20.880
+and for that, I basically use 
+
+00:18:20.880 --> 00:18:22.240
+my own judgment.
+
+18:22.240 --> 18:24.880
+This is based typically on the fact that
+
+18:24.880 --> 00:18:27.760
+this is just a very short name, 
+
+00:18:27.760 --> 00:18:32.000
+and most local identifiers use short names,
+
+18:32.000 --> 18:34.400
+whereas item values used for dynamic scoping
+
+18:34.400 --> 18:36.720
+typically have a package prefix
+
+18:36.720 --> 00:18:37.679
+or something like this.  
+
+00:18:37.679 --> 00:18:38.960
+So the fact that it's a short name
+
+00:18:38.960 --> 00:18:40.880
+gives me a good idea.
+
+18:40.880 --> 00:18:41.520
+Here in this case, 
+
+00:18:41.520 --> 00:18:42.640
+I actually look at the code, 
+
+00:18:42.640 --> 00:18:45.600
+and we see that there's nothing in here
+
+18:45.600 --> 00:18:47.039
+that may actually refer 
+
+00:18:47.039 --> 00:18:48.080
+to this variable `widget`, 
+
+00:18:48.080 --> 00:18:49.280
+so I think it's safe,
+
+18:49.280 --> 00:18:51.360
+but in the general case, 
+
+00:18:51.360 --> 00:18:54.400
+we may look here and be surprised,
+
+18:54.400 --> 00:18:55.760
+or, you know, you may call out 
+
+00:18:55.760 --> 00:18:58.320
+the functions which may themselves end up
+
+18:58.320 --> 19:00.080
+referring to this variable.
+
+19:00.080 --> 19:02.640
+So sometimes we need to investigate a
+
+19:02.640 --> 19:03.840
+little more.
+
+19:03.840 --> 19:05.919
+We are most of the time not completely sure
+
+19:05.919 --> 19:07.520
+whether the result is correct or not,
+
+19:07.520 --> 00:19:09.520
+of course, so the other thing 
+
+00:19:09.520 --> 00:19:10.640
+you may want to check 
+
+00:19:10.640 --> 00:19:12.160
+is also uses of things 
+
+00:19:12.160 --> 00:19:14.400
+like `eval` or `symbol-value`.
+
+19:14.400 --> 19:17.200
+So it's often a good idea to search,
+
+19:17.200 --> 00:19:18.799
+and you do a search of `eval`, 
+
+00:19:18.799 --> 00:19:21.490
+and you see here it's using `eval`.  
+
+00:19:21.490 --> 00:19:24.160
+Hmmm... Okay, so what does this `eval` do?
+
+19:24.160 --> 00:19:25.760
+It's evaluating expressions 
+
+00:19:25.760 --> 00:19:28.240
+that appear in `args` here
+
+19:28.240 --> 19:31.840
+so you can see where those args come from,
+
+19:31.840 --> 00:19:35.120
+and we see here, these are expressions 
+
+00:19:35.120 --> 00:19:36.840
+that don't do anything very special.
+
+19:36.840 --> 19:41.520
+It's just using `make-supplicant-choice`,
+
+19:41.520 --> 19:44.960
+and `make-supplicant-choice` itself
+
+19:44.960 --> 19:47.120
+just doesn't refer to `widget`, for example,
+
+19:47.120 --> 19:50.000
+so you know we should be safe,
+
+19:50.000 --> 19:52.559
+but while I'm here...
+
+19:52.559 --> 19:53.840
+okay, well, then we can do that later.
+
+19:53.840 --> 19:55.679
+Well, that's actually the next warning,
+
+19:55.679 --> 00:19:58.080
+exactly. So here we see that this is 
+
+00:19:58.080 --> 00:20:00.000
+using the dynamically-scoped dialect,
+
+00:20:00.000 --> 00:20:02.799
+so we convert it to lexical-scoped.
+
+20:02.799 --> 20:04.559
+Of course, this may introduce errors,
+
+20:04.559 --> 20:07.200
+but we hope it doesn't.
+
+20:07.200 --> 20:08.880
+And actually, it was a good change here,
+
+20:08.880 --> 20:12.080
+because if you see again,
+
+20:12.080 --> 00:20:14.240
+this actually evals expressions
+
+00:20:14.240 --> 00:20:16.159
+that appear here in `args`,
+
+20:16.159 --> 20:18.480
+and so these are expressions
+
+20:18.480 --> 20:21.039
+that are passed here.
+
+20:21.039 --> 20:23.679
+So this expression here used to be
+
+20:23.679 --> 00:20:24.480
+evaluated with dynamic scoping, 
+
+00:20:24.480 --> 00:20:28.000
+even though it appears to be normal code
+
+00:20:28.000 --> 00:20:29.760
+within this file, which says 
+
+00:20:29.760 --> 00:20:32.559
+it's using lexical scoping,
+
+20:32.559 --> 20:34.400
+and so there are some remnants
+
+20:34.400 --> 20:36.640
+of dynamic scoping all over the place
+
+20:36.640 --> 00:20:37.840
+in Emacs still, because we have
+
+00:20:37.840 --> 00:20:43.679
+those calls of `eval` with a nil argument.
+
+20:44.880 --> 20:47.039
+Here we have `cons`...
+
+20:47.039 --> 20:50.400
+that needs to be `hash quoted`.
+
+20:52.400 --> 00:20:54.080
+Oh, and we have a reference 
+
+00:20:54.080 --> 00:20:56.720
+to this variable `enwc-edit-id'. 
+
+00:20:56.720 --> 00:20:57.520
+So this is clearly 
+
+00:20:57.520 --> 00:21:00.400
+a dynamic-scoped variable.
+
+21:00.400 --> 21:02.000
+We can either add a `defvar`
+
+21:02.000 --> 21:03.440
+to silence the warning,
+
+21:03.440 --> 00:21:06.799
+or maybe we can `require` the package.
+
+21:06.799 --> 21:10.080
+The file that defines it...
+
+21:14.080 --> 21:17.360
+So let's see where it's defined.
+
+21:17.360 --> 21:21.200
+Here it's defined in `enwc.el`,
+
+21:21.200 --> 00:21:23.440
+so I'm going to try just to add
+
+00:21:23.440 --> 00:21:25.039
+the dependency.
+
+21:25.039 --> 00:21:27.840
+I'm going to `require` here. This is risky.
+
+21:27.840 --> 21:30.159
+We'll see when we compile a file later,
+
+21:30.159 --> 21:32.320
+we may get a circular dependency
+
+21:32.320 --> 21:34.720
+because of it.
+
+21:34.720 --> 21:36.320
+If that's the case, we're going to
+
+21:36.320 --> 00:21:38.320
+have to remove this `require` 
+
+00:21:38.320 --> 00:21:42.000
+and instead put `defvar`s.
+
+21:42.000 --> 21:42.559
+Sometimes it's worth actually
+
+21:42.559 --> 21:44.640
+looking further at the various files
+
+21:44.640 --> 00:21:48.080
+to see how to redefine the dependencies
+
+21:48.080 --> 21:49.840
+to break those circular dependencies,
+
+21:49.840 --> 21:52.320
+but it's often not really
+
+21:52.320 --> 21:54.720
+worth the trouble.
+
+21:55.679 --> 00:21:58.400
+Oh, no, that's not what-- 
+
+00:21:58.400 --> 00:22:01.440
+I'm not going to the right place... 
+
+00:22:01.440 --> 00:22:07.039
+Here I was. So here `edit-map`.
+
+22:07.039 --> 22:09.760
+Well, we can probably...
+
+22:09.760 --> 22:12.159
+it may disappear or...
+
+22:12.159 --> 22:13.760
+oh, I see.
+
+22:13.760 --> 22:16.320
+Okay, so this `edit-map` actually is
+
+22:16.320 --> 22:18.559
+defined in this very file.
+
+22:18.559 --> 00:22:20.240
+It's just that it's defined later. 
+
+00:22:20.240 --> 00:22:21.600
+So all we need to do 
+
+00:22:21.600 --> 00:22:24.320
+is to move this definition
+
+00:22:24.320 --> 00:22:27.200
+to before its first use,
+
+22:27.200 --> 22:28.960
+since otherwise it's going to be taken
+
+22:28.960 --> 22:33.520
+as lexically-scoped, which we don't want.
+
+22:33.520 --> 22:35.360
+And while I'm here, I see this `copy-keymap`.
+
+22:35.360 --> 22:38.400
+I don't like `copy-keymap`,
+
+22:38.400 --> 22:40.960
+so I'm going to change this
+
+22:40.960 --> 22:44.080
+to a normal keymap,
+
+22:44.080 --> 22:46.159
+and then I'm just going to use
+
+22:46.159 --> 22:50.080
+`set-keymap-parent` instead of `copy-keymap`
+
+22:50.080 --> 00:22:51.600
+to get basically the same result,
+
+00:22:51.600 --> 00:22:55.280
+but without having copied anything.
+
+22:55.280 --> 22:57.760
+And this one will disappear...
+
+22:57.760 --> 23:00.240
+this one as well-- or should hopefully,
+
+23:00.240 --> 23:03.360
+thanks to the `require`.
+
+23:03.360 --> 23:09.840
+Here we have a `hash` missing,
+
+23:09.840 --> 00:23:11.840
+and we have some functions
+
+00:23:11.840 --> 00:23:14.000
+which are unknown,
+
+23:14.000 --> 00:23:14.666
+so let's see... 
+
+00:23:14.666 --> 00:23:18.240
+Where is this function defined?
+
+23:18.240 --> 23:21.679
+Nowhere.  Huh, wonderful, okay.
+
+23:21.679 --> 00:23:25.200
+So we'll just leave it like it is, 
+
+00:23:25.200 --> 00:23:27.120
+and that's going to be 
+
+00:23:27.120 --> 00:23:31.360
+for the author of the package to fix.
+
+23:31.360 --> 23:37.120
+How about this one?
+
+23:37.120 --> 23:40.240
+Oh, okay, so it's defined in `enwc.el`
+
+23:40.240 --> 00:23:41.679
+so presumably, 
+
+00:23:41.679 --> 00:23:44.559
+this is going to disappear as well.
+
+23:50.159 --> 23:51.030
+One more...
+
+23:56.159 --> 23:58.640
+Okay, so this one
+
+23:58.640 --> 23:59.919
+is just like the previous one.
+
+23:59.919 --> 24:04.000
+We're going to leave it at that.
+
+24:04.000 --> 24:06.720
+And this is it!  Huh, wonderful.
+
+24:06.720 --> 24:10.000
+So let's recompile.
+
+24:16.080 --> 24:23.520
+Oh, we have a warning for `fin`.
+
+24:25.679 --> 00:24:28.640
+This variable seems not to be used
+
+00:24:28.640 --> 00:24:32.000
+anywhere in the file, so we're just
+
+24:32.000 --> 00:24:33.440
+going to remove it.  
+
+00:24:33.440 --> 00:24:34.880
+I leave it there just in case 
+
+00:24:34.880 --> 00:24:36.000
+someone needs later on 
+
+00:24:36.000 --> 00:24:37.679
+to look for a `fin` variable 
+
+00:24:37.679 --> 00:24:39.760
+to see where it used to be.
+
+24:39.760 --> 24:41.600
+Again, you know, maybe it's actually used...
+
+24:41.600 --> 24:43.519
+yeah, dynamic scoping somehow,
+
+24:43.519 --> 24:46.159
+but given the short name,
+
+24:46.159 --> 24:48.960
+I presume this is not the case.
+
+24:48.960 --> 24:51.200
+Here, oh, that's the code removed
+
+24:51.200 --> 24:52.559
+that had a hash missing.
+
+24:52.559 --> 24:54.159
+That's the one that's not defined.
+
+24:54.159 --> 24:56.799
+This one is not defined,
+
+24:56.799 --> 24:58.000
+and this is it.
+
+24:58.000 --> 25:03.039
+Let's make a last recompilation
+
+25:03.039 --> 25:06.080
+to see if we missed yet something else.
+
+25:06.080 --> 25:07.919
+Nope, and that's it, okay.
+
+25:07.919 --> 25:11.200
+Well, here we go; we're done.
+
+25:11.200 --> 00:25:14.240
+Okay so this was it.  
+
+00:25:14.240 --> 00:25:15.440
+You've seen, I think,
+
+25:15.440 --> 25:18.000
+pretty much examples of all of those,
+
+25:18.000 --> 25:20.159
+and I hope you enjoyed it.
+
+25:20.960 --> 25:22.580
+Lessons to take home:
+
+25:22.580 --> 25:23.919
+use the byte compiler.
+
+25:23.919 --> 25:26.000
+You can also use `flymake-mode` instead.
+
+25:26.000 --> 00:25:31.600
+I recommend enabling it as much as you can,
+
+25:31.600 --> 25:33.520
+and head the warnings.
+
+25:33.520 --> 25:35.440
+Follow the warnings. Try to fix them.
+
+25:35.440 --> 25:37.200
+If you can fix all of the warnings,
+
+25:37.200 --> 00:25:38.080
+it's always much better, 
+
+00:25:38.080 --> 00:25:39.200
+because then the new warnings 
+
+00:25:39.200 --> 00:25:40.960
+really show up.
+
+25:40.960 --> 25:42.880
+And once you've done it, it's really
+
+25:42.880 --> 00:25:44.559
+kind of-- because there's always 
+
+00:25:44.559 --> 00:25:46.799
+new things coming up.
+
+25:46.799 --> 25:48.799
+And I think this is it.
+
+25:48.799 --> 00:25:50.720
+I hope you liked it, and thank you 
+
+00:25:50.720 --> 00:25:56.000
+for attending this presentation. Bye.
+
+00:25:56.000 --> 00:25:57.000
+[captions by Hannah Miller] 
-- 
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