How can I change the format of relative numbers?

Question

I use this plugin relative-line-numbers of Fanael on Github. how to add extra spaces on the both sides of the relative number sides?

Form this

To this

Answer 1

From the documentation:

relative-line-numbers-format is a variable defined in ‘relative-line-numbers.el’. Its value is relative-line-numbers-default-format

Documentation:
The function used to format the line numbers. The function should take one integer argument: the line’s distance, in lines, from the current line, and return a string.

You can customize this variable.

You will have first to define somewhere in your configuration file, a function to use for formatting, for example:

(defun my-relative-line-numbers-default-format (offset)
  "The default formatting function.                                                                                        
Return the absolute value of OFFSET, converted to string."
  (concat " - " (number-to-string (abs offset)) " + "))

Then, you will have to call M-x customize-variable then type relative-line-numbers-format. You'll be shown a window inside with you can change the name of the function used for formatting, use your custom function defined above. Then you'll have to apply and save.