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Editors (Vim)

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course link: Editors (Vim)

Vim has multiple operating modes.

  • Normal: for moving around a file and making edits
  • Insert: for inserting text
  • Replace: for replacing text
  • Visual (plain, line, or block): for selecting blocks of text
  • Command-line: for running a command

Basics

Inserting text

From Normal mode, press i to enter Insert mode.

Now, Vim behaves like any other text editor, until you press<ESC> to return to Normal mode.

Buffers, tabs, and windows

Vim maintains a set of open files, called “buffers”.

A Vim session has a number of tabs, each of which has a number of windows (split panes).

Each window shows a single buffer. Unlike other programs you are familiar with, like web browsers, there is not a 1-to-1 correspondence between buffers and windows; windows are merely views.

A given buffer may be open in multiple windows, even within the same tab.

This can be quite handy, for example, to view two different parts of a file at the same time.

By default, Vim opens with a single tab, which contains a single window.

Command-line

Command mode can be entered by typing : in Normal mode.

Your cursor will jump to the command line at the bottom of the screen upon pressing :.

This mode has many functionalities, including opening, saving, and closing files, and quitting Vim.

  • :q quit (close window)
  • :w save (“write”)
  • :wq save and quit
  • :e {name of file} open file for editing
  • :ls show open buffers
  • :help {topic} open help
    • :help :w opens help for the :w command
    • :help w opens help for the w movement

Vim’s interface is a programming language

Movement

Movements in Vim are also called “nouns”, because they refer to chunks of text.

  • Basic movement: hjkl (left, down, up, right)
  • Words: w (next word), b (beginning of word), e (end of word)
  • Lines: 0 (beginning of line), ^ (first non-blank character), $ (end of line)
  • Screen: H (top of screen), M (middle of screen), L (bottom of screen)
  • Scroll: Ctrl-u (up), Ctrl-d (down)
  • File: gg (beginning of file), G (end of file)
  • Line numbers: :{number}<CR> or {number}G (line {number})
  • Misc: % (corresponding item)
  • Find: f{character}, t{character}, F{character}, T{character}
    • find/to forward/backward {character} on the current line
    • , / ; for navigating matches
  • Search: /{regex}, n / N for navigating matches

Selection

Visual modes:

  • Visual: v
  • Visual Line: V
  • Visual Block: Ctrl-v

Can use movement keys to make selection.

Edits

Vim’s editing commands are also called “verbs”, because verbs act on nouns.

  • i enter Insert mode
    • but for manipulating/deleting text, want to use something more than backspace
  • o / O insert line below / above
  • d{motion} delete {motion}
    • e.g. dw is delete word, d$ is delete to end of line, d0 is delete to beginning of line
  • c{motion} change {motion}
    • e.g. cw is change word
    • like d{motion} followed by i
  • x delete character (equal do dl)
  • s substitute character (equal to cl)
  • Visual mode + manipulation
    • select text, d to delete it or c to change it
  • u to undo, <C-r> to redo
  • y to copy / “yank” (some other commands like d also copy)
  • p to paste
  • Lots more to learn: e.g. ~ flips the case of a character

Counts

You can combine nouns and verbs with a count, which will perform a given action a number of times.

  • 3w move 3 words forward
  • 5j move 5 lines down
  • 7dw delete 7 words

Modifiers

You can use modifiers to change the meaning of a noun.

Some modifiers are i, which means “inner” or “inside”, and a, which means “around”.

  • ci( change the contents inside the current pair of parentheses
  • ci[ change the contents inside the current pair of square brackets
  • da' delete a single-quoted string, including the surrounding single quotes

Customizing Vim

Vim is customized through a plain-text configuration file in ~/.vimrc (containing Vimscript commands).

Here is the basic configuration file that provided by this course.

VimL
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" Comments in Vimscript start with a `"`.

" If you open this file in Vim, it'll be syntax highlighted for you.

" Vim is based on Vi. Setting `nocompatible` switches from the default
" Vi-compatibility mode and enables useful Vim functionality. This
" configuration option turns out not to be necessary for the file named
" '~/.vimrc', because Vim automatically enters nocompatible mode if that file
" is present. But we're including it here just in case this config file is
" loaded some other way (e.g. saved as `foo`, and then Vim started with
" `vim -u foo`).
set nocompatible

" Turn on syntax highlighting.
syntax on

" Disable the default Vim startup message.
set shortmess+=I

" Show line numbers.
set number

" This enables relative line numbering mode. With both number and
" relativenumber enabled, the current line shows the true line number, while
" all other lines (above and below) are numbered relative to the current line.
" This is useful because you can tell, at a glance, what count is needed to
" jump up or down to a particular line, by {count}k to go up or {count}j to go
" down.
set relativenumber

" Always show the status line at the bottom, even if you only have one window open.
set laststatus=2

" The backspace key has slightly unintuitive behavior by default. For example,
" by default, you can't backspace before the insertion point set with 'i'.
" This configuration makes backspace behave more reasonably, in that you can
" backspace over anything.
set backspace=indent,eol,start

" By default, Vim doesn't let you hide a buffer (i.e. have a buffer that isn't
" shown in any window) that has unsaved changes. This is to prevent you from "
" forgetting about unsaved changes and then quitting e.g. via `:qa!`. We find
" hidden buffers helpful enough to disable this protection. See `:help hidden`
" for more information on this.
set hidden

" This setting makes search case-insensitive when all characters in the string
" being searched are lowercase. However, the search becomes case-sensitive if
" it contains any capital letters. This makes searching more convenient.
set ignorecase
set smartcase

" Enable searching as you type, rather than waiting till you press enter.
set incsearch

" Unbind some useless/annoying default key bindings.
nmap Q <Nop> " 'Q' in normal mode enters Ex mode. You almost never want this.

" Disable audible bell because it's annoying.
set noerrorbells visualbell t_vb=

" Enable mouse support. You should avoid relying on this too much, but it can
" sometimes be convenient.
set mouse+=a

" Try to prevent bad habits like using the arrow keys for movement. This is
" not the only possible bad habit. For example, holding down the h/j/k/l keys
" for movement, rather than using more efficient movement commands, is also a
" bad habit. The former is enforceable through a .vimrc, while we don't know
" how to prevent the latter.
" Do this in normal mode...
nnoremap <Left>  :echoe "Use h"<CR>
nnoremap <Right> :echoe "Use l"<CR>
nnoremap <Up>    :echoe "Use k"<CR>
nnoremap <Down>  :echoe "Use j"<CR>
" ...and in insert mode
inoremap <Left>  <ESC>:echoe "Use h"<CR>
inoremap <Right> <ESC>:echoe "Use l"<CR>
inoremap <Up>    <ESC>:echoe "Use k"<CR>
inoremap <Down>  <ESC>:echoe "Use j"<CR>

For macos, There might not have the default .vimrc file in ~.

But never mind, just type vim ~/.vimrc and paste the code into it, then type :wq.

You will find that everything is done!

Extending Vim

copy lecture notes...need review

There are tons of plugins for extending Vim. Contrary to outdated advice that you might find on the internet, you do not need to use a plugin manager for Vim (since Vim 8.0). Instead, you can use the built-in package management system. Simply create the directory ~/.vim/pack/vendor/start/, and put plugins in there (e.g. via git clone).

Here are some of our favorite plugins:

We’re trying to avoid giving an overwhelmingly long list of plugins here. You can check out the instructors’ dotfiles (Anish, Jon, Jose) to see what other plugins we use. Check out Vim Awesome for more awesome Vim plugins. There are also tons of blog posts on this topic: just search for “best Vim plugins”.

Resources

Exercises

Warning

I will write my own solution to the problem, If you want to solve those by yourself, please stop.

Problem1

Complete vimtutor. Note: it looks best in a 80x24 (80 columns by 24 lines) terminal window.


Solution

Bash
1
vimtutor

Problem2

  • Install and configure a plugin: ctrlp.vim.

    1. Create the plugins directory with mkdir -p ~/.vim/pack/vendor/start
    2. Download the plugin: cd ~/.vim/pack/vendor/start; git clone https://github.com/ctrlpvim/ctrlp.vim
    3. Read the documentation for the plugin. Try using CtrlP to locate a file by navigating to a project directory, opening Vim, and using the Vim command-line to start :CtrlP.
    4. Customize CtrlP by adding configuration to your ~/.vimrc to open CtrlP by pressing Ctrl-P.


Solution

...TO DO

Problem3

To practice using Vim, re-do the Demo from lecture on your own machine.

Here is a broken fizz buzz implementation:

Python
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def fizz_buzz(limit):
    for i in range(limit):
        if i % 3 == 0:
            print('fizz')
        if i % 5 == 0:
            print('fizz')
        if i % 3 and i % 5:
            print(i)

def main():
    fizz_buzz(10)

fix the following issues:

  • Main is never called
  • Starts at 0 instead of 1
  • Prints “fizz” and “buzz” on separate lines for multiples of 15
  • Prints “fizz” for multiples of 5
  • Uses a hard-coded argument of 10 instead of taking a command-line argument


Solution

  1. G move to the bottom of the file
  2. o create a new line
  3. insert code:
    Python
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    if __name__ == '__main__':
    main()
  4. /limit search for limit, then press n to move to the next match
  5. i enter insert mode, and change limit to 1, limit + 1
  6. /fizz search for fizz, then press n to move to the next match.
  7. ci' change the inner text of ', insert buzz
  8. move the cursor to the print('fizz') line, press $, then i enter insert mode and insert , end=''
  9. jj. move the cursor to line 6 and make the same change as previous did
  10. gg move the cursor to the top of the file, O create the new line above，and insert import sys
  11. /10 find 10, then ci( change the text in (, type int(sys.argv[1])

The final result:

Python
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import sys

def fizz_buzz(limit):
    for i in range(1, limit + 1):
        if i % 3 == 0:
            print('fizz', end='')
        if i % 5 == 0:
            print('buzz', end='')
        if i % 3 and i % 5:
            print(i)

def main():
    fizz_buzz(int(sys.argv[1]))

if __name__ == '__main__':
    main()

Problem4

(Advanced) Convert XML to JSON (example file) using Vim macros. Try to do this on your own, but you can look at the macros section above if you get stuck.


Solution

...TO DO