[Tutor] Enable Python feature in vim editor

[Cameron Simpson]

On 23Nov2021 10:01, Leam Hall <leamhall at gmail.com> wrote:
>When I first learned Python, the "whitespace is significant" thing made 
>a lot of sense. After that my shell, Perl, and Ruby code looked a lot 
>like my Python.  :)  I've been on a Go phase for a bit, and those are 
>Go settings, to match "go fmt". I'd agree though, for Python I prefer 
>two spaces as indent, and no tabs in code at all.

I've got quite a lot in my vi and vim settings, so I'll run through the 
things I've got which seem applicable to Python (and coding in general):

First my "vi" settings (sourced by my vimrc):

    set autoindent

Great for almost all coding; remember that at the start of a line ^D 
(ctrl-D) steps you backwards one indent step when you need to 
out-indent. I've got some autoindenting syntax stuff turned on too, so 
often I instead write the next line, let the auto stuff mangle the 
intended indent, and adjust with "<<" to left shift the line.

Oh, were you aware of the "<" and ">" keystrokes? Like many vim 
commands, followed by a cursor motion (or doubled to just affect the 
current line). So "<<" shifts the current line, "<}" shifts the lines 
from here the next empty line (great for shifting a whole code block), 
"20<<" shifts the next 20 lines including the current one, etc. It 
honours the "shiftwidth" setting below; mine is set to 2.

Note that having autoformatting (see below) reduces the need for this, 
but it is still very useful - I use it a lot. Including to indent the 
settings listing for this message!

    set autowrite

Writes the file when I switch to another, so switching files is just ":n 
filename". I pretty much always use revision control, so I am not very 
hung up on unwanted changes - a diff will always show them to me.

    set ignorecase

Just makes searching easier all around. Note that a mixed case search 
has a degree of case sensitivity anyway, so when you care about the case 
you can be more precise.

    " set nomesg
    set nowrapscan

I like to know when I've hit the last match instead of cycling to the 
top of the file - in a big file that isn't always obvious.

    set showmatch

Bounces the cursor to the matching bracket when you type a closing 
bracket, and also highlights the starting bracking. Quite ahndy.

    set shiftwidth=2

Doesn't everyone indent (and therefore shift) by 2 spaces?

    " set tabstop=8
    set tabstop=4

Not too big, not too small. I use expandtabs, so I don't embed TABs in 
my code.

    set noterse
    set writeany

Goes with autowrite.

    map! \c cs at cskk.id.au
    map! \C Cameron Simpson <\c>

Handy for writing my email address.

    " Markdown: `code` a word
    map `` lbi`ea`

I write MarkDown docstrings and like MarkDown in general for a lot of 
simple doco. This defines a `` macro to put backticks around the current 
word, very handy for embedding "computer names" in text.

    map!  :stop
a
    map! 
 
a
    map!  i
    map!  lli
    map! 
 I

Suspend (^Z) and some emacs-like cursor motions. The suspend is pretty 
ancient, I think that works transparently in vim these days. And I 
rarely suspend in a multiwindow/multitab/multipane environment.

    map # :n #
z.

So handy. Switch between this file and the previous with a single 
keystroke.

    map g Gz.

I find typing an uppercase G to go to a line tiresome.

    map t :ta 

"t" shorthand for :td (go to tag). I use tagfiles agressively, and they 
work well in Python. Note that ctags also makes tags for filenames, so 
finding a source file in a large hierarchy is also much easier. I've got 
a couple of shell scripts to make regenerating tags files easier too:

    https://hg.sr.ht/~cameron-simpson/css/browse/bin/ctags-update

and a shell function "uptags" to run it:

    uptags () {
         >> tags
         ctags-update -o tags ${1+"$@"}
         ls -ld tags
     }

Note in particular the ctags options I use at the bottom of 
"ctags-update".

Then the vim settings:

    source ~/rc/vi

Of course.

    set encoding=utf-8
    scriptencoding utf-8

This is the way.

    set bg=dark
    colorscheme cameron
    syntax reset
    syntax on

Colours.

    set autoread

See and load the file if it is not modified and the original changes.  
This means I can have multiple vims watching the same file. I 
reflexively save quite often (and autosave above does it a lot too) so 
my buffers are usually unmodified.

    set backupcopy=yes

I write in place (hard link paranoia) so a backup is handy during 
rewrites.

    set clipboard=autoselect

Doesn't work as well as I've like.

    set cursorline

I find it useful to highlight the current line - I've usualy got at 
least 2 buffers visible so this aids not losing track.

    set expandtab

Of course. I sometimes like TABs to typing an indent, but not for the 
text itself, which should have spaces.

    set fileformats=unix,mac,dos

Just cope and don't mangle things.

    set ignorecase
    set incsearch

Nicer searching.

    set list
    set listchars=tab:▸\ ,trail:_,extends:>,precedes:<,conceal:*

Stuff I like visible in "list" mode.

    set mouse=
    set mousefocus=on
    set mousehide
    set mousemodel=extend

What I've landed on for mouse integration. I found the other modes 
either annoying or not working seamlessly. In particular I like to 
GUI-level copy/paste with the mouse and mouse integration broke that 
just for the vim windows, so annoying.

    set nofsync

Overuse of fsync is just bad.

    set scrolloff=2

2 lines of text visible at the top/bottom of the screen WRT to the 
cursor line.

    set smartcase

I think this is the clever "mixed case searches are case senstivie" 
thing.

    set t_Co=256

I've got a 256 colour terminal emulator (IIRC).

    set ttyfast

An ancient setting I think.

    set updatetime=2000

Polling interval for external changes?

    set wildignore+=*.swp,*.zip,*.exe,*.a,*.o,*.pyc
    set wildmenu wildmode=list:longest

Files to ignore when autocompleting filenames.

    map <C-W><C-T> :split %<CR>
    map <C-W><C-N> :new<CR>:n 

"vim window mode", so useful. I use ^W^T to do a horizontal split 
(matches with Cmd-Shift-T in iTerm to do that same with panes), ^W^V for 
a vertical split (atches with Cmd-Shift-V in iTerm). I've got similar 
bindings in tmux, too.

    map ,f :silent !format %



The big winner. Macro to autoformat this file using a code formatter.  
The "format" script is my own, here:

    https://hg.sr.ht/~cameron-simpson/css/browse/bin-cs/format

which runs my preferred formatter (language specific) on the file. See 
the script for details, write your own! Or adopt and adapt!

    autocmd CursorHold * checktime | call feedkeys("")
    autocmd FocusGained,BufEnter * :checktime

These are tickers to drive the automatic detection of external changes.  
So useful!

    " Remove ALL autocommands for the current group.
    " autocmd!
    autocmd BufWritePost *.go :silent !echo; format -t .autoformat %
    autocmd BufWritePost *.php :silent !echo; format -t .autoformat %
    autocmd BufWritePost *.js :silent !echo; format -t .autoformat %
    autocmd BufWritePost *.py :silent !echo; format -t .autoformat %

This automatically autoformats various file extensions on save, _if_ the 
source tree has a nonempty ".autoformat" file in it. So I go:

    echo 1 >.autoformat

in my code tree and off we go! There are trees where you don't want 
magic autoformatting, particularly existing codebases where you don't 
want autoformat noise in your commits.

    let @t=system('tags=$(findup tags) || tags=tags; echo "set tags=$tags"')
    @t

Set the "tags" vi/vim setting if you've just made a fresh tags file.

    autocmd BufWritePost * :let @t=system('vim-ctags-update ' . shellescape(@%))
    autocmd BufWritePost * :@t
    autocmd BufWritePost * :redraw!

Update the tags when you save a file.

    autocmd BufRead,BufNewFile haproxy* set ft=haproxy

Recognise an addition file syntax based on filename.

    if has("gui_macvim")
      set macthinstrokes
    endif

Setting for GUI Vim on a Mac, I never use it.

Cheers,
Cameron Simpson <cs at cskk.id.au>