Question

I thought it would be handy to create a mapping that would turn the current line or visually selected line into a comment banner.

Something like this:

This is the description of the usage of the class

would become, after pressing a shortcut:

/*----------------------------------------------------*/
/* This is the description of the usage of the class  */
/*----------------------------------------------------*/

Answer 1

I have this line in my ~/.vimrc that does exactly what you want:

nnoremap <leader>g I/* <Esc>A */<Esc>yyp0llv$r-$hc$*/<Esc>yykPjj

Place your cursor on a line, press <leader>g, done.

The default <leader> is \, so that would be \g.

You can, obviously, use any shortcut you want.