VIM Editor Issue 14

"Linux Gazette...making Linux just a little more lovable!"

Pick an Editor, Any Editor

By Jens Wessling, jwesslin@erim.org

im (VI iMproved)

One day I realized that I seem to spend an inordinate amount of time in front of a computer screen and more precisely with a text editor in front of me. This should hardly have been a surprise to me considering I work with computers for eight to ten hours a day and then I go home and spend several more. I guess that this obvious fact finally struck home with me. I would guess I spend about 20-30 hours a week in a text editor alone. With some quick calculations I realized that this adds up to over 1000 hours a year. That is over 40 solid days of my life every year in an editor. (That is a conservative estimate.) This realization spurred me to try to optimize the time I spend in my editor.

The first step I took was to try and find the best editor around. I started asking around to see who used what and to try to find out what the important qualities of an editor were. Don't make this mistake. Editors are one of the most religious beliefs a programmer holds. Every programmer is convinced that there's is the best. My office-mate uses PICO, some of my co-workers use EMACS, VI, SlickEdit, or any one of an unending list. Every person I talked to insured me that their selection was by far the best. When I inquired about the differences, they were primarily insignificant. That was when I learned the horrible truth. Most editors are essentially equivalent. No matter how hard people insist, most editors have more features than any user will ever use. (Except PICO). In the Linux community, these selections basically fall in to one of two categories. VI clones, or Emacs. My recommendation is that everyone learn one of these well. It doesn't really matter which one, just pick one, stick with it and use it. (Religiously if you must.)

I have gone to great lengths to learn VIM, a VI clone. And certainly if not THE best, one of the top contenders. Many features are shared among VI clones, basically the VI subset. The additional features are basically individual to each clone. VIM comes with most, if not all, Linux distributions. The home page for VIM is http://www.math.fu-berlin.de/~guckes/vim/. VIM is in active development and is getting better by the day. Syntax highlighting should be out, if not by the time you read this, then soon thereafter.

I will assume that most people know the basics of VI and want to change it from a simple tool to a powerful one. I will share some of the handy tips and tricks I use.

Programming, Tabs, and Tags.
ctags is a marvelous utility for C and C++ Programmers. ctags comes with the VIM distribution. What this utility does is create a list of all the subroutine names in the files you specify and allow you to jump to the given subroutine while in you editor with just one keypress. The way you run ctags is simple.


ctags *.c
or
ctags *.cpp

Then, crank up your editor and move to wherever it is you call any subroutine from and press [CTRL]-]. This will take you immediately to wherever the routine is, even if it is in a different file.

File Switching
I frequently work with several files concurrently and I need to switch between these files continually. The command to switch to another file in VIM is ":e fn". The shortcut to switch to the last file edited is ":e #". This is fine for normal use, but I switch files often, and 4 keystrokes seems like a bit much. This is where VIM's key mapping comes in. VIM like most editors has an rc file. It is called .vimrc, what a shock. 8) In this file I have the following command.

 
" Save and switch to other buffer.
map N :w [CTRL]-M

This command lets me switch buffers with a single keypress. The other nice feature in VIM for switching between files is tab completion for file names. The way tab completion works is to take whatever letters you have typed in so far on for the file name and find all of the files that could possibly match. Hitting tab will scroll through the list of files until you find the one you want. If no beginning letters are specified for the file name, it will scroll through them all.

Mapping
I do a LOT of coding and I find that I often need to comment out blocks of lines. I have developed 2 macros for handling this with a minimum of effort.

 
map C 0i/*[CTRL-ESC]A*/[CTRL-ESC]j
map T 0xx$xxj

If you examine the first line, you will see that it does the following.

Moves to the beginning of the line
Enters Insert Mode
Places "\*" there
Escapes to command mode
Adds "*/" to the end of the line
Escapes to command mode
Moves down One line

The second line does the following.

Moves to the beginning of the line
Removes 2 characters
Moves to the end of the line
Removes 2 characters
Moves down One line

I can type "12C" in command mode and it will comment out the next dozen lines. and "12T" will uncomment a dozen lines that were commented by "C".

Keep in mind that when you remap keys, they lose there original values. In this case, "C" was an odd Delete until end of line and next several lines into a given buffer, and "T" was a command I can't really figure out from the documentation. I don't really miss these two but be careful that you don't map "i" or "x" or anything else you might need later.

Have fun with this. I hope to have more later.
jEnS Wessling