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Anti-pattern of vimrc

file encoding

In Vim script, :scriptencoding exists to specify a file encoding. Generally it should define :scriptencoding when you use multibyte character. When you don't use multibyte character, you don't have to define :scriptencoding. Therefore you have to use :scriptencoding at the head of your vimrc.

Bad pattern

" use multibyte charactor.
let g:indentLine_char = '|'

Good pattern

scriptencoding utf-8
let g:indentLine_char = '|'

:scriptencoding and :set encoding

Vim can not recognize the character code of your vimrc when :scriptencoding is defined before :set encoding. When writing :set encoding, it should be described before :scriptencoding.

Bad pattern

scriptencoding utf-8
set encoding=utf-8

Good pattern

set encoding=utf-8
scriptencoding utf-8

Abbreviate option

I often see a vimrc using an abbreviate option and the same strict option. It's a bad coding. You should use a strict option only.

Bad pattern(1)

" 'modeline' of abbreviation.
set ml

Good pattern(1)

set modeline

Bad pattern(2)

augroup vimrc
  " 'autocmd' of abbreviation.
  au!
  au FileType vim  * :set expandtab
augroup END

Good pattern(2)

augroup vimrc
  autocmd!
  autocmd FileType vim  * :set expandtab
augroup END

If you don't know an abbreviate option, please you try :h ml in your Vim. And you will know a strict name of the abbreviate option.

   *'modeline'* *'ml'* *'nomodeline'* *'noml'*

Scope of variable

I often see a vimrc using g:mapleader and mapleader. It's a bad coding. You should use a variable with a scope.

Bad pattern(1)

let mapleader = ' '

Good pattern(1)

let g:mapleader = ' '

Bad pattern(2)

for i in range(0,2)
  execute printf('source .local_%d.vim', i)
endfor

Good pattern(2)

for s:i in range(0,2)
  execute printf('source .local_%d.vim', s:i)
endfor

When you use a variable without a scope outside a function, implicitly its scope is global scope(g:). Generally when you use a variable outside a function, you have to define it with script scope(s:).

:autocmd without belonged to groups

In Vim script, :autocmd exists. Its syntax is following syntax.

:au[tocmd] [group] {event} {pat} [nested] {cmd}

:autocmd can omit [group]. It is a bad coding and that makes your Vim heavy.

Bad pattern

autocmd FileType cpp setlocal expandtab
autocmd FileType make setlocal noexpandtab

Good pattern

" define a group `vimrc` and initialize.
augroup vimrc
  autocmd!
augroup END

" register autocmds to group `vimrc`.
autocmd vimrc FileType cpp setlocal expandtab
autocmd vimrc FileType make setlocal noexpandtab

Why is it heavy?

If you define autocmds without a group, your Vim registers the same autocmd each :source ~/.vimrc. And your Vim executes the same autocmds each occurring a Event(e.g. FileType). In one word, it's heavy.