Vim Help Integration

This is the fourth post in my series on using Vim to do C# development. You can read the introduction into why someone might want to do that here.

The last post on Vim Intellisense talked about using ctags to navigate to the definition of a class/method and read the documentation there. This covers any code you, or your company, has written, but it leaves out all of the .NET framework's objects. That's a pretty big oversight.

The problem is we need to know what methods exist on a .NET object, or what parameters a .NET object accepts, or just general help on a certain .NET object. This information is all easily obtained from the MSDN library, a largely under utilized resource as most developers I know depend primarily on Intellisense instead.

To solve this, we'll setup Vim so that you can put the cursor on any word and hit F1 and Vim will automatically open your browser of choice and do a search of the MSDN library for that word. To do this, add the following to your vimrc:

" setup integrated help
function! OnlineDoc()
let s:wordUnderCursor = expand("<cword>")

if &ft =~ "cs"
let s:url = "http://social.msdn.microsoft.com/Search/en-US/?Refinement=26&Query=" . s:wordUnderCursor
else
execute "help " . s:wordUnderCursor
return
endif

let s:browser = "\"C:\\Program Files\\Mozilla Firefox\\firefox.exe\""
let s:cmd = "silent !start " . s:browser . " " . s:url

execute s:cmd
endfunction

map <silent> <F1> :call OnlineDoc()<CR>
imap <silent> <F1> <ESC>:call OnlineDoc()<CR>

Notice that I use firefox, and that the help site to use is determined based on the file extension of the current file. This allows you to set this up for any language you work with. Finally, if the extension isn't defined it'll open up Vim's help.