Irreal

Mike Zamansky has posted another video in his Using Emacs Series. This video looks at playing music with MPD and Emacs. Of course, Emacs can’t play music on its own but it can be used to control music players, effectively moving music playing functions into Emacs.

MPD provides the server side of a music playing client/server system so you have to choose a client (the player) as well. There are lots of clients available and Zamansky considers three that leverage the MPC player and integrate well with Emacs. He tried but didn’t like the built-in Emacs MPC mode and Mingus. The video shows them both in action so you can decide for yourself if they work for you. Finally, Zamansky demonstrates a player that he did like: simple-mpc. It has a simple interface that is explicitly modeled after that of mu4e so it will be familiar to those using mu4e for their email.

All of this is really intended for Linux but as far as I can tell it’s possible to make it work with macOS as well. Apple, of course, has the iTunes player—which despite what many say, I find easy to use and flexible. I keep my music collection (mainly) on my iMac but AirPlay makes it possible to stream music to my laptop or other Apple device. All in all, I’m happy with the Apple solution.

Still, I like moving everything possible into Emacs so I’ve added a TODO to investigate getting MPD running on my Mac. I know that MPD can run on a different machine from the player so I could still have my centralized music collection. If anyone has any experience with MPD on Macs, please leave a comment.

The video runs just short of 15 minutes so you can probably watch it on a break. As usual with Zamansky’s videos, it full of information and definitely worth watching.

Alexey Koval has a nice post on Emacs as a devops editor. It’s from a little over a year old but it’s still worth taking a look at. I’m not involved with devops but I still learned a few useful things from the post and accompanying videos.

For example, Koval shows how to debug shell scripts from Emacs using bashdb. That can be really handy when your script is more than a few lines long. Of course, you can also run the script from inside Emacs and test things as you go along. In that respect, it’s another example of interactive programming, a method that I find especially useful.

He also has a nice section on using tramp to work with remote files. I tend to do stupid things like opening an SSH session to list the files to find the name of the file I want but as Koval shows, you can just open the remote directory you’re interested in to get a dired listing from which you can pick whatever file you need. Once you’ve got a remote session going, you can even start a remote shell that reuses the same SSH connection that tramp is using.

There are 7 short videos in the post that illustrate the points Koval’s making. My only complaint about them is that he doesn’t have a key display utility so it’s sometimes hard to follow what he’s doing. Nonetheless, the videos are really useful and I learned some new tricks from them.

The post is definitely worth looking at even if you’re not involved with devops.

Chris Wellons over at Null Program has another great post. It considers how to define and use structures in Emacs Lisp. What I like most about the post is that it starts with the obvious solution of using a list to hold the structure and accessing the elements of the structure with the nth function or something similar but notices the problems that such a strategy can bring.

One such problem is that it’s hard to remember which slots in the list corresponds to which items in the structure. This is especially hard on readers but can also trip up the original author. Another issue with using the nth strategy is that it effectively freezes the slot positions and makes it hard to modify the program.

To solve these problems, Wellons introduces some accessor functions to access the structure items by name. Then he does the same thing for setting the functions by making them settable with setf. At that point, he’s got a pretty nice solution but has written a lot of boiler plate. He observes that a natural solution is to write a macro to write all the boiler plate and says that Emacs, of course, has already done this with the cl-defstruct macro.

Most Elisp programmers have probably used cl-defstruct but never thought much about why it exists or how it works. That’s what’s great about Wellon’s post: it shows how cl-defstruct grows naturally out of finding a solution for a common need and the problems that the obvious solution to that need entails.

The rest of Wellon’s post considers changes coming in Emacs 26. If you do any Elisp programming at all, you should definitely read this post. It’s full of good information—way more than I’ve discussed here—and news of what we can expect, as far as structures are concerned, in Emacs 26.

I always think of my Emacs configuration as a Japanese garden: it’s always underway but never reaches perfection. The other day, I saw this tweet:

What has emacs replaced in your life? https://t.co/5adbsfy8bz #emacs

— /r/Emacs (@EmacsReddit) February 11, 2018

and followed the link hoping to discover something else I could replace with Emacs.

It’s amazing how many applications people have replaced with Emacs but sadly the list of things people had replaced fell into two categories:

1. Things I had already replaced;
2. Things I hadn’t replaced because I don’t use them.

Still, I haven’t given up hope and will continue searching for things I can bring under the Emacs umbrella. After all, the point of a Japanese garden is that it is never finished.

I’ve been happily using Interleave to takes notes while reading PDFs ever since I read about it in Piotr Limanowski’s excellent post on Reading for Programmers. It’s a great way to take notes that are synchronized with the PDF.

Gonçalo Santos has produced a similar system, org-noter, that provides much of the same functionality as well as some others. I temporarily loaded it so I could try it out. One thing from the documentation that I liked about it was that it can remember your place in the PDF so that it’s easy to take up where you left off. With Interleave, I do that by making a temporary note that I delete when I continue reading. Sadly, I couldn’t get that feature of note-taker to work. I’m probably doing something wrong but it’s not obvious what.

Other than a couple of minor items in the way it handles the notes buffer, it operates pretty much like Interleave. There are not enough differences to get me to switch but if you haven’t loaded either yet, it’s worthwhile trying them both out.

If you’ve used org-noter and have thoughts on it, please leave a comment and enlighten us all.