Keeping Tabs With Emacs | Exploring Emacs

I have a hazy memory of the first time I ever fired up Emacs, not knowing my Meta key from my elbow. That was a long time ago now, but I vaguely recall the experience of not knowing how to do the first thing, not even opening a file, followed by many months of slowly developing fluency, building up my mental model of how Emacs works and my muscle memory of keystrokes.

While Emacs contains immense potential for the experienced user, there is an initial investment of time and energy required before you can do even fairly simple editing tasks. Fortunately it is the self-documenting editor, so everything you need to know to use it is right there in Emacs itself. But then of course you first have to learn its documentation features.

Over the years, the Emacs maintainers have taken steps to present a more familiar face to this strange beast, adding modern interface features such as toolbars, menus and scrollbars. But there is a certain level of experience you reach when you no longer need such modern trappings, and once you have enough of the most useful keybindings memorized, you find you can navigate the system better using just your fingers.

There is an exception to the rule that Emacs's keyboard-centric design obviates the need for user-friendly window dressing. That exception is tabbed navigation. Tabs, meaning simply a set of views that you can switch between, are a modern feature that is actually a useful addition to your workflow rather than merely a way to make Emacs less bewildering to the uninitiated.

In recent versions of Emacs, tabbing functionality is supplied by Tab Bar mode. As it happens, tab bar mode is not enabled by default in GNU Emacs, but toggling it on is as simple as M-x tab-bar-mode.

So what is it about tabs that make them a desirable feature rather than just more screen noise? For me, tabs are a necessary means for organizing my workflow. But before we get into that, we should take some time to discuss how the Emacs display system works. This is necessary because Emacs is a system with a history going back decades, since before many of the current conventions around computing were developed. It uses an idiosyncratic terminology for some common features, which means that part of developing familiarity with Emacs involves learning some new vocabulary.

Buffers, Windows and Frames

In Emacs terminology, a buffer is a data structure that stores text data, such as might be found in a file on disk containing source code. In Emacese, a buffer that holds data from a file is said to "visit" that file. But it is by no means limited to text files; it might be input to and output from a running program such as a shell; it might be information displayed by Emacs itself, such as command completion options. It includes the character data along with editor information such the mark, point and region, themselves Emacese vocabulary terms whose explication will have to wait for another day, but briefly are all related to cursor position.

To display a buffer, you need a window. And here the terminology gets a little tricky, because a window in Emacs is not the familiar desktop environment window that can be opened, closed, minimized and resized; not what you are used to from every other program you have ever worked with. Emacs uses the term frame for that concept, while windows are the sections within the frame that display the contents of a particular buffer.

At any given time, Emacs can have any number of buffers open, and can be displaying all or a subset of them in windows within one or more frames. To put it in relational terms, windows have a one-to-one relationship to frames, and buffers have a one-to-many relationship to windows, in that multiple windows, potentially in multiple frames, can be displaying the contents of the same buffer. Learning to manage your buffers and windows is a basic Emacs skill, necessary for navigating Emacs's unique interface.

Buffer Bloat

One of the consequences of this arrangement is that a buffer does not necessarily have a window associated with it at any given time. This is another way that Emacs does not follow familiar conventions. What we expect when using, for example, Visual Studio Code, is that if you have a file open, then there is a tab open displaying its contents.

But in Emacs, a buffer does not always have a window displaying it, and there is the tendency for open buffers to accumulate as you work, to the point where finding the one you want in the *Buffer List*, brought up with C-x C-b, becomes a tedious process of scanning the list for the one you have in mind, maybe while trying to remember what that particular buffer was named.

Window Layouts

Then there is the configuration of the open windows, which can be laid out to match your workflow. For example, when writing code, you might want a frame split in half vertically so that the source has plenty of display space on the left-hand window, while the right-hand window is again split horizontally, with the upper half containing some documentation and the lower half displaying a terminal emulator. This is the kind of layout you might have in a tmux session, which similarly has a concept of tabs, although it uses the terminology of panes in windows.

In Emacs it is easy enough to set this configuration up, but then when you want to switch to a different configuration, you need to change the buffer associated with each window and possibly also update their layout. Being the programmable editor that it is, you could certainly script this out in elisp, but what if there were a more general way to switch between multiple sets of window configurations? What if there was a better way to keep tabs on all your open buffers?

A Better Way

When you have several of some set of things you want ready at hand, you need some way to organize them while at the same time making them easy to access. A multi-level hierarchy of nested containers, such as in a file system, has its uses, but when we are talking about tools that you want at hand, ready to be pulled out of your toolbox without having to spend time searching through it, you want a simple organization scheme with no more than one level. When the tools you are talking about are files and programs, then you need some way of grouping them so that related items go in the same bucket. And that is what tab bar mode provides.

Tabs mean being able to quickly switch between contexts, rather than being required to hunt through a list of open buffers and redoing your window layout with each context switch. This is nothing new of course, and Emacs was in a way late to this game, only incorporating the tab bar in version 27, released in 2020. This was likely because this functionality was previously provided by various elisp packages, but in any case, it is so useful that it makes sense to include it out of the box.

Really the interface of tab-like boxes at the top of the screen is not strictly necessary, even if the interface is named after them. The important thing is the ability to quickly switch between window layouts, which like everything else in Emacs can all be done using the keyboard. You can create new tabs, close existing ones and switch between them, managing whole window configurations just as you would individual windows. Seemingly a simple feature, but one that I personally have found a welcome change from digging through the buffer list each time I want to switch to a different task.

The Tab Line

Interestingly, in addition to the more familiar kind of tab mentioned above, Emacs also comes with a feature called the Tab Line, which is similar to tab bar mode but functions differently. It displays a set of tabs above each window, one for each of the buffers visited by that window, in the order that they would be visited using the buffer movement keybindings C-x <left> and C-x <left>. This particular feature does not have the workflow optimization benefits that the tab bar does, but is something to be aware of and maybe give it a try. It is activated with M-x global-tab-line-mode.

The Code

To set it up so that tab bar mode is enabled when your Emacs session starts up, add the following to your init file:

  ;; Enable tab bar mode
  (tab-bar-mode 1)

And if you feel ready for the real Emacs zen experience of letting go of familiar interface window dressing and letting your fingers do the work, add the following:

  ;; Turn off the menu bar
  (menu-bar-mode 0)
  ;; Turn off the tool bar
  (tool-bar-mode 0)
  ;; Turn off scroll bars
  (scroll-bar-mode 0)

Next Up

Tabs are a nice, practical feature to have in your Emacs arsenal. What is next on our Exploring Emacs journey? Learn some elisp programming? A useful major mode? Some obscure but cool feature? There are so many possibilities. I'm a kid in a candy store. Until next time!