Replace every character on a visual selection with a register's character

Question

I'll try to illustrate as clear as I can.

Suppose I have the following text open in vim/nvim

 _________
|         |
|  9999   |
|         |
 ---------

If select 9999 visually and then hit r8, this will happen

 _________
|         |
|  8888   |
|         |
 ---------

Can I do the same replacing character(s) with another one that's on a register, mostly my system clipboard ? Suppose I wanted to change the vertical bars on the box's border, replacing | with │ and making something like

 _________
│         │
│  8888   │   <--- The bars are little longer though it may seem simliar to before
│         │
 ---------

I am aware that I can do this by selecting the box and using a substitute command, s/|/│/g but that is not what I want. Furthermore, I don't think this method would work properly on visual block mode (with a vertical selection).

So, is there a way to do this using r followed by something?

Answer 1

Standard "r" command does not accept register argument. But you can write some mapping of your own if you really like so. For example,

xnoremap <expr>r v:register is '"' ? 'r' : 'r'..getreg()[0]

Then (in visual mode) if pressing "r" without register override (and also clipboard option is neither "unnamed" nor "unnamedplus") it still works as usual. But if used with non-default register, like "+r, then it just takes the first char from that register and never waits for user input.

Answer 2

If you visually select (block select Ctrlv) the first vertical bar and type:

r│

The the bar will be replaced:

 _________
│         |
│  8888   |  
│         |
 ---------

If you repeat the operation on the other bar:

 _________
│         │
│  8888   │  
│         │
 ---------

Answer 3

A substitution would work well, see :help \%V.

As for your immediate problem, it can be solved with a bit of lateral thinking… and whatever you usually press to paste from the system clipboard (Ctrl+V, Cmd+V, etc).

Here it is Cmd+V:

If your Vim is built with clipboard support, then you can place what you want in register + and paste it from the system clipboard as above:

:let @+ = @a

Answer 4

In your specific example where you're only replacing a single character with the contents of a register you can use s instead of r and insert the register contents via CTRL-R:

Without making a visual selection, type sCtrl-R+Esc.

This technique won't work for replacing multiple characters with the register contents, like when you convert 9999 into 8888 earlier in your question. For that, you need Matt's answer.