Is it possible to make a numerically-prefixed hotkey run a function that many times?

Question

I find that if you enter a numeric prefix prior to executing an ex command, the convention that it applies is to set up the command to prep an operation across a line range. It is explained in the documentation,

A NUMBER OF LINES

When you know how many lines you want to change, you can type the number and then ":". For example, when you type "5:", you will get:

    :.,.+4

Now you can type the command you want to use. It will use the range "." (current line) until ".+4" (four lines down). Thus it spans five lines.

Now what I am dealing with is a custom function of mine, this one:

function! MyAmazingEnhancedDot()
    if v:hlsearch == 1
        :normal! .n
    else
        :normal! .j
    endif
endfun

This is just a way to streamline repetitive tasks that include repeating an operation on a range of lines or over a series of search matches.

This function is bound to a hotkey. Such as Alt+. or whatever.

My aim is to be able to do something very powerful: I should be able to type /varName<CR>ciwnew-var<ESC>n9<Alt+.> to achieve renaming 10 instances of varName to new-var.

What actually happens if I do this is that it does not perform the renaming and the 9 lines are manipulated with my .-saved edit operation from column 0.

I can only assume that Vim is interpreting my keystrokes thus: :.,.+8 normal! .n.

On the glass-half-full side, the :normal! .j case of the bind actually works, because the j motion having no effect is of no consequence in this situation. (I still need the j to make it work in a non-numeric-prefixed interactive use case).

So my question is how can I override the line-expansion behavior that Vim applies to my bind? What would be fantastic is if I can read in the numeric prefix as an argument or something like that.

Answer 1

By default vim treats all functions as if they are default ex commands, i.e. any prefixed numbers are used as {range}. To change this you need to modify your function and your map to use a count.

Map with count

Maps can take a count and are made available via v:count and v:count1. The first contains 0 if no count is provided and the later contains 1 as the default. You can create a map to your function:

nnoremap <M-.> :<C-u>call MyAmazingEnhancedDot(v:count1)<cr>

For more info :h v:count

Commands with count

Commands can have the option of either a {range} or a count as a prefix. When creating the command the flag -count disables the range option and defaults the <count> variable to 0. Optionally a default value can be provided -count=N. The prefix value is then available via the variable count in your function.

A command using count would look like this:

:command -count=1 EDot call MyAmazingEnhancedDot(<count>)

Now when you call 9EDot your function is called with the count of 9 instead of a range.

For more info see :h command-count

Both examples

Here is your code:

function MyAmazingEnhancedDot(count)
  let c = a:count
  while c > 0
    if v:hlsearch == 1
      :normal! .n
    else
      :normal! .j
    endif
    let c -= 1
  endwhile
endfunction

command -count=1 EDot call MyAmazingEnhancedDot(<count>)

nnoremap <M-.> :<C-u>exe v:count1 . "EDot"<CR>

Now you can do your example

/varName<CR>ciwvar-name<esc>n9<M-.>