Irreal

I just had one of those “Well Duh! Of course” moments. It came to me with this Emacs Command of the Day tweet:

M-x read-only-mode, bound to C-x C-q.

Avoid accidentally modifying a buffer with this handy minor mode!

— Ⓔ Command of the Day (@ecotd) November 28, 2017

I always think of Ctrl+x Ctrl+q as turning off read-only-mode in a grep or Dired buffer. See Mike Zamansky’s video on Dired for an example of the latter. But, of course, what it really does is toggle read-only-mode so if you want to put a buffer in view-mode to prevent inadvertent changes you can just use Ctrl+x Ctrl+q to turn it on.

In my post the other day on Mike Zamansky’s Dired video, I meant to mention one of the packages he talked about but I forgot. That package is pcre2el, a package to, among other things, convert Perl compatible regular expressions to Emacs-style regular expressions. Many people have trouble with Emacs’ regular expressions because of their syntax. They were originally optimized for working with Lisp so some of the escaping rules are just the opposite of Perl’s (and other) regular expression systems. For example, in most regex systems, parentheses are used for grouping and if you want a literal parenthesis, you have to escape it. Because parentheses are ubiquitous in Lisp, the rule is exactly the reverse for Emacs regexes. These days, of course, most people aren’t writing in Lisp so these rules don’t appear to make sense and are annoying.

For those who find this confusing or annoying, the pcre2el package offers a partial solution. The package is essentially a translator that parses Perl regexes and translates them into Emacs regexes. The two engines are different; Perl regexes have capabilities that Emacs regexes don’t so the Perl syntax supporting those features can’t be translated. Still, if you’d like to work with the Perl syntax instead of switching back and forth, this package may be just what you need. Take a look at Zamansky’s video to see an example of it in action.

If you’ve been wanting to get a copy of Mickey Petersen’s excellent Mastering Emacs, here’s your chance:

You don't need a new TV – what you DO need is my book on Mastering #Emacs. It's just $20 for the next 4 days! Click the link below to activate the 50% off coupon:https://t.co/yH5hohw44j pic.twitter.com/Mgpai0XzbX

— Mickey Petersen (@mickeynp) November 24, 2017

If you’re an Emacser or want to be one, this is the book for you.

Mike Zamansky has his latest video up. This time it’s about Dired. Dired is one of the great features of Emacs but many users are only dimly aware of it and don’t make full use of its capabilities. Zamansky’s video is an excellent introduction to some of those capabilities. One of those features, writable dired, is extraordinarily useful and something I use all the time. Zamansky has a nice demonstration of using it to rename several files at once.

One feature that Zamansky didn’t mention is doing a regular expression search on a set of files by marking them in Dired and then typing A. You can also do a query replace by typing Q. There are many more commands like these—take a look at the GNU Dired reference card for details.

As with all of Zamansky’s videos, this one is definitely worth your time, especially if you aren’t using Dired regularly. The video is about 16 and a third minutes long so you’ll need to put aside some time for it.

A couple of years ago, I wrote about Josh Stella’s use of Emacs by a CEO. I’m always interested in how non-technical people use Emacs so I took note when Stella’s piece popped up again. I reread his post and mine and have to say that I didn’t really do justice to Stella’s post. It’s really excellent and you should give it a read if you haven’t already.

There’s an interesting discussion of the post on the Emacs reddit that’s also worth reading. Stella joined the conversation and said he would write a followup to his original post. I look forward to reading that and will, doubtless, write about it when it appears.

I really like ivy-occur and the way you can take a list of Ivy completion candidates and put it in a separate buffer that you can manipulate in any of the usual Emacs ways. The easiest way to use it is to type Ctrl+c Ctrl+o in a selection list.

It turns out that you can customize what gets put in the ivy-occur buffer for a specific command by writing a function to fill the buffer and registering it with Ivy. One really nice example is that is set by default is the swiper command. You can do a Swiper search and capture all the candidates with ivy-occur. That’s useful if you want to interact with more than one of the selections but what’s really nice is that the buffer inherits grep-mode and can be made writable with the usual Ctrl+x Ctrl+q. That makes it really easy to make multiple changes to a buffer, especially if you leverage something like iedit or multiple-cursors.

Recently, abo-abo announced a new ivy-occur customization: this time for find-file type commands. It results in the occur buffer becoming a Dired buffer. That means you can use the power of Dired to manipulate the list of files. As a real-world example, I often preview my blog posts locally in my browser. That causes the post to be rendered in HTML and placed in a file that the browser can display. Ideally, I delete that file after I publish the post but I usually forget and end up with several useless HTML files in my posts directory.

I used to deal with that by bringing up Dired, typing * . html to mark all the HTML files and then delete them by typing D. With the abo-abo’s latest change I can just type Ctrl+x Ctrl+f html$ to get a list of the HTML files and then Ctrl+c Ctrl+o t D y to delete them.

Follow the link to abo-abo’s post for all the details. And if you aren’t already using Ivy/Counsel/Swiper, you really should try them out. As I keep saying, they are my most useful package.

UPDATE [2017-11-21 Tue 15:48]: git-mode → grep-mode

Derek Banas has posted a nice introduction to Emacs video. It covers roughly the same material as the built-in tutorial with the addition of setting up a Clojure programming environment. Banas covers installing Emacs on both macOS and Windows. One of the commenters complained that he didn’t cover setting it up on Linux but it’s hard to imagine a Linux user not knowing how to install an application. He uses version 25.3 of Emacs so he’s working with an up-to-date Emacs.

Watching the video really brought home how much we all customize our Emacsen. Since he was using a stock install, he didn’t have things like minibuffer completion for file names and commands. It seemed painfully slow compared to how we work when we have something like Swiper/Counsel/Ivy or Ido/Smex installed.

My major complaint is that he used “window” and “frame” interchangeably. That distinction is confusing enough for n00bs without adding to the entropy in an introductory video. On the other hand, the production values for the video are excellent. It was very professionally done, including seamless switching between macOS and Windows.

If you’re an experienced Emacs user, the video probably won’t tell you anything you don’t already know but it’s an excellent resource for beginners. The video is a few seconds over 52 minutes so you’ll have to schedule time for it.