Starting

I didn’t know the Vim language.

But I’m writing a blog, and I wanted to enable spell checking. I found on the Internet this:

:setlocal spell spelllang=en

Nice, but it is a long command, let’s create a key binding:

map <space>s :setlocal spell! spelllang=en<CR>

Writing this in .vimrc and reloading the editor (or running :source ~/.vimrc to reload the config) we should be able to toggle the spell checking pressing SPACE s.

Notes:

• the ! after spell means toggle and inverts the state of the parameter
• <CR> is carriage return (enter)

One step further

Now why not print a message when the check is enabled or disabled? To run multiple instruction we can use a function:

let s:is_spell_active = 0
function SpellLoop()
    let s:is_spell_active = !s:is_spell_active
    setlocal spell! spelllang=en

    if s:is_spell_active
        echo "spell check enabled"
    else
        echo "spell check disabled"
    endif
endfunction

map <silent> <space>s :call SpellLoop()<CR>

Notes:

• variables with name starting with s: are visible only in the current script file, the ones starting with g: are globals and with l: are locals (the l: can be omitted, but it’s useful to avoid conflict with reserved variable names)

• <silent> prevent the printing of called command, we want to display stuff from the function

More languages

We can also write a function to loop over different languages:

let s:spell_list = ["en", "it"]
let s:spell_i = 0

function SpellLoop()
    let s:spell_i = (s:spell_i + 1) % len(s:spell_list)
    let l:spell = s:spell_list[s:spell_i]

    exec "setlocal spell spelllang=" . l:spell

    echo "spell check: " . l:spell
endfunction

And support the “none” language too:

let s:spell_list = ["none", "en", "it"]
let s:spell_i = 0

function SpellLoop()
    let s:spell_i = (s:spell_i + 1) % len(s:spell_list)
    let l:spell = s:spell_list[s:spell_i]

    if l:spell == "none"
        setlocal spell!
    else
        exec "setlocal spell spelllang=" . l:spell
    endif

    echo "spell check: " . l:spell
endfunction

Make a plugin

Everything can be packet in a plugin putting the code in a .vim file inside ~/.vim/plugin/

To change the languages list from .vimrc we have to define s:spell_list as global with the g: and check if it is already defined before setting the default value

if !exists('g:spell_list')
    let g:spell_list = ["none", "en"]
endif

The full plugin can be downloaded from GitHub here