As developers, programmers, engineers—whatever you want to call us—we spend a lot of time programming. And seeing as we spend more waking hours with our editors than we do with our families, it's important that we take a close look at that experience and make sure that we're getting the most out of it that we can.
DISCLAIMER: This post is targeted at the Emacs crowd. If you're not an Emacs user, I hope that you can at least still learn a thing or two from this list and maybe find a way of achieving the same functionality in your own editor. If this list happens to provoke an interest in switching over, great. But this post is not intended to persuade readers one way or the other—simply to share some heavily used features that can make those hours away from home a little bit happier.
In Emacs, the customization comes from your ~/.emacs configuration file. Emacs users spend years building up these config files, and a senior developer's .emacs file can be a highly sought-after resource. (One of my last correspondences with a departing engineer consisted of "Good luck," and "Can I get the path to your .emacs?") With that in mind, I've listed some useful key bindings to pass on where applicable.
Figure 1: Evidence of generational learning through .emacs configuration files.
1. goto-line
Even the superhuman developer likely spends at least half of his time debugging code. And although some IDEs will highlight the failing line, it's not always a compiler that's flagging a problem. Whether it's grepping through a list of files or simply looking for a problematic section of code that someone brought to your attention, the "goto-line" operation is all too frequent.
(define-key global-map (kbd "M-g l") 'goto-line)
2. revert-buffer
Ever re-run a program after making a bug fix? How about 20 times a day? Having a quick way to reload a run-time log (or any frequently changing file) can be a huge time-saver.
(global-set-key (kbd "C-S-r") 'revert-buffer)
3. The macro
Serious developer know well the power of the macro. Non-power programmers cringe at the thought of it. The concept of the macro tends to evoke a sense of heavy up-front cost that's only useful in the rarest, most tedious circumstances. But in a given day, a few good macros may save you an hour of work. (If your managers knew how much time you waste by not using macros, they would insist on it!)
We could spend pages discussing the use cases of macros, but suffice it to say that for pretty much any task which takes more than 10 seconds and will be repeated at least 10 times in one sitting, you're better off using a macro. In Emacs, this couldn't be easier:
- Start recording: C-x (
- Do whatever you want to repeat, using regular expressions and generic operations wherever possible.
- End recording: C-x )
- Run the macro n times: C-u n C-x e
This whole process creates a throwaway macro that you can keep until you create a new one. If, however, you decide that it's generic and useful enough to save for later, this bit of config code will help:
(defun save-macro (name) "save a macro. Take a name as argument and save the last defined macro under this name at the end of your .emacs" (interactive "SName of the macro :") ; ask for the name of the macro (name-last-kbd-macro name) ; use this name for the macro (find-file user-init-file) ; open ~/.emacs or other user init file (goto-char (point-max)) ; go to the end of the .emacs (newline) ; insert a newline (insert-kbd-macro name) ; copy the macro (newline) ; insert a newline (switch-to-buffer nil)) ; return to the initial buffer
4. increment-number-at-point
The true Emacs user will look at an incredibly tedious task like generating repeating blocks of code with sequentially incrementing numbers with enthusiasm! When recording the macro, simply place the cursor over the applicable number and increment-number-at-point:
(defun increment-number-at-point () (interactive) (skip-chars-backward "0123456789") (or (looking-at "[0123456789]+") (error "No number at point")) (replace-match (number-to-string (1+ (string-to-number (match-string 0)))))) (global-set-key (kbd "C-c +") 'increment-number-at-point)
Note that the same can be achieved for hexadecimal numbers as well: http://www.emacswiki.org/emacs/IncrementNumber
5. ansi-term
This one is my personal favorite. Couple the macro with a terminal embedded in your editor, and you're poised to be the most powerful developer in the office. Once your terminal is contained within your editor (and once you've spawned several simultaneous terminals in there too), you'll realize you no longer have reason to live outside the editor (though your spouse may disagree).
My typical development environment is a split window with code on one side and a terminal on the other (all within a single Emacs instance). Using the "C-x o" key binding I can then quickly switch between editing and performing the usual command line operations in Linux.
Like I said, this is where the beauty of Emacs truly starts to come together. Ever had a bunch of errors dumped to the terminal that you need to cross reference with your code to apply a series of fixes? Automate that! Suppose that the compiler is complaining about a bunch of variables in our code not being declared yet. Easy:
- In the terminal buffer grep for "Error:"
- Use a regex to search for the variable name, and copy it.
- Switch over to the code buffer with C-x o.
- Declare the variable, and make a new line.
- Switch back to the terminal.
- Rinse and repeat.
Note that in Emacs, there are a variety of terminal types you can use. I prefer the ansi-term mode due to its smooth support of telnet, but I'm sure there are ways of customizing the other terminals (e.g. shell-mode) to behave in the same way as my beloved ansi-term.
6. rename-buffer
Since I'm typically working on five different tasks at once, it helps to have named buffers to keep track of things. This becomes even more useful when I want to switch to a specific terminal with a specific environment in a specific directory:
M-x rename-buffer
Emacs will then prompt you for a new name for the buffer. Then getting to the file/terminal you need doesn't involve sifting through tens of windows and tabs. Simply…
C-x b <name of buffer>
Note also that if you don't provide the name of the buffer, you can simply press RETURN to view a searchable list of open buffers, which helps if you can't remember what a file was called. This is also useful if you want to, say, have a macro quickly close all buffers matching a given regex.
7. Auto indent
Ever carefully align every block of code to paint your file like a Georges Seurat? If so, you're wasting your time. Even with a preexisting poorly formatted file from another developer, there's no need to do any heavy lifting. Kick back and let your editor do it for you. In Emacs simply highlight the lines you want and…
C-M-\
Done.
8. upcase/downcase-region
Ever need to change a bunch of variables to constants or vice versa? In most circumstances, this involves changing the case, and Emacs makes this very easy for us. Simply select the applicable text and "C-x-u" to convert to uppercase or "C-x-l" to convert to lowercase. You'll also need to add these lines to your .emacs:
(put 'downcase-region 'disabled nil) (put 'upcase-region 'disabled nil)
One can also imagine how useful this would be if you wanted to convert an entire file from underscore-based variable names to CamelCase or vice versa. Combining this case-conversion functionality with macros would make the task a trivial operation.
9. The Mark Ring
Rarely does a file of code fit on a single page. So it should come as no surprise that a reasonable amount of the average developer's time is spent navigating back and forth between pages in a file. Often this operation consists of either paging up or down or grepping for a phrase near the line of interest (not to mention the dreaded journey from keyboard to mouse!).
Luckily, Emacs remembers where we've been. If you know you're going to come back to your current location in a file, simply "C-<SPC> C-<SPC>" to push the current point onto the "mark ring," and "C-u C-<SPC>" to pop it off. Emacs will take you back to where you left off. (Note that if it's a multi-hop trip, you can push multiple points onto the mark ring to retrace each step on your way back home.)
10. Dired (File Explorer)
If you're still browsing for files in your terminal—or worse, a GUI—you're missing out. Because Emacs serves as an interactive file explorer too. Simply "C-x-f" to open a file, but press RETURN without supplying a name, and Emacs will open a buffer with a listing of the current directory. From there, you can navigate through the directory with cursor keys, regular expressions, or even (horrified gulp) the mouse to find what you're looking for.
11. The regex
Finally, no list would be complete without mention of regular expressions. Although it may go without saying, the regex search within your editor is such a commonplace necessity that most of us may take it as second nature—almost a cyborgial extension of the developer's motoneural system. I would imagine that very few real editors out there lack regex searching, but for the record, it's achieved in Emacs via "C-M-s" for forward/downward search and "C-M-r" for reverse/upward search.
Well, I hope that helped. These were just the few Emacs features that I use on a regular enough basis that I couldn't go without them. Please leave comments with suggestions on items I might have forgotten. As is often the case with these sorts of things, it's the actions we take for granted that, by definition, we are most likely to overlook.