Different text width in the same filetype in vim -

i editing markdown files wich contain code examples (like here). there way tell vim, when editing markdown files, set textwidth=80 exept keep code syntax? example:

here text within markdown file // textwidth=80      puts 'hello world' // textwidth not specified 

i don't know how set tw option meet requirement. came function, want:

function! wrapmd()    let x=&tw    let &tw=80    normal! gqq    let &tw=x endfunction 

this function format tw=80 on current line, after restores original tw setting.

you can source function (or put in vimrc), , do:

:v/\v^( {4}|\t)/call wrapmd() 

at time when want format md text.

you create mapping or put in autocmd on event bufwritepre.

here made gif when test function: