• Use @@ to set the unnamed register, for example:

    let @@ = "example contents of the unnamed register"
  

  • v:count: The count given for the last Normal mode command.

  • Variables used inside a function are local unless prefixed by something like g:, a:, or s:

  • When a function reaches endfunction or return is used without an argument, the function returns zero.

  • There can be no comment after map, abbreviate, execute and ! commands.

  • The :source command reads Ex commands from a file line by line. You will have to type any needed keyboard input. The :source! command reads from a script file character by character, interpreting each character as if you typed it.

  • Print the word under the cursor: echo expand("<cword>")

  • i_CTRL-R: select a register to insert from.

  • Note that in line 28 noremap is used to avoid that any other mappings cause trouble. Someone may have remapped call, for example. In line 24 we also use noremap, but we do want <SID>Add to be remapped. This is why <script> is used here. This only allows mappings which are local to the script: map-<script> The same is done in line 26 for noremenu.

      24 noremap <unique> <script> <Plug>TypecorrAdd  <SID>Add
      ...
      28 noremap <SID>Add  :call <SID>Add(expand("<cword>"), 1)<CR>
    

  • Add a command:

    38 if !exists(":Correct")
    39      command -nargs=1  Correct  :call s:Add(<q-args>, 0)
    40 endif
    

  • unlet: This is especially useful to clean up used global variables and script-local variables (these are not deleted when the script ends). Function-local variables are automatically deleted when the function ends.

Mapping An Operator map-operator

An operator is used before a {motion} command. To define your own operator you must create mapping that first sets the operatorfunc option and then invoke the g@ operator. After the user types the {motion} command the specified function will be called.

g@{motion} Call the function set by the operatorfunc option. The '[ mark is positioned at the start of the text moved over by {motion}, the '] mark on the last character of the text. The function is called with one String argument: line {motion} was linewise char {motion} was characterwise block {motion} was blockwise-visual

Although block would rarely appear, since it can only result from Visual mode where g@ is not useful.

Here is an example that counts the number of spaces with <F4>:

      nmap `<silent>`{=html} `<F4>`{=html} :set opfunc=CountSpaces`<CR>`{=html}g@ vmap `<silent>`{=html} `<F4>`{=html} :`<C-U>`{=html}call CountSpaces(visualmode(), 1)`<CR>`{=html}

      function! CountSpaces(type, ...) let sel_save = &selection let &selection = "inclusive" let reg_save = @@

          if a:0  " Invoked from Visual mode, use gv command.
            silent exe "normal! gvy"
          elseif a:type == 'line'
            silent exe "normal! '[V']y"
          else
            silent exe "normal! `[v`]y"
          endif

          echomsg strlen(substitute(@@, '[^ ]', '', 'g'))

          let &selection = sel_save
          let @@ = reg_save

      endfunction

Note that the selection option is temporarily set to inclusive to be able to yank exactly the right text by using Visual mode from the '[ to the '] mark

Replace a series of asterisk bullet points with a numbered list

    :let c=0 | g/^* /let c+=1 | s//\=c.'. '

First it initializes the variable c then it executes the global command g which looks for the pattern ^* Whenever a line containing this pattern is found, the global command executes the command let c+=1 | s//\=c.'. ' It increments the variable c, then it substitutes (//) with the evaluation of an expression (\=): the contents of variable c concatenated (.) with the string '. '

• If you don’t want to modify all the lines from your buffer, but only a specific paragraph, you can pass a range to the global command. For example, to modify only the lines whose number is between 5 and 10:

    let c=0 | 5,10g/^* /let c+=1 | s//\=c.'. '
  

To make a command, you can use:

    command! -range=% NumberedLists let [c,d]=[0,0] | <line1>,<line2>g/^/let [c,d]=[line('.')==d+1 ? c+1 : 1, line('.')] | s//\=c.'. '

Variables

The scope name by itself can be used as a Dictionary. For example, to delete all script-local variables:

    :for k in keys(s:)
    :    unlet s:[k]
    :endfor

The behavior of == depends on a user’s settings.

• ==? is the “case-insensitive no matter what the user has set” comparison operator
• ==# is the “case-sensitive no matter what the user has set” comparison operator.