Add duplicate (yank, comment, and put) operation.

doc/commentary.txt

@@ -29,6 +29,26 @@ gcu
                                                 *:Commentary*
 :[range]Commentary      Comment or uncomment [range] lines
 
+In addition, you can yank a section of text before commenting it out:
+
+gcy{motion}             Yank and then comment or uncomment the lines that
+                        {motion} moves over.
+
+gcy                     Yank and then comment or uncomment [count] lines.
+
+{Visual}gcy             Yank and then comment or uncomment the highlighted
+                        lines.
+
+You can also duplicate a section of text before commenting it out:
+
+gcd{motion}             Duplicate and then comment or uncomment the lines that
+                        {motion} moves over.
+
+gcd                     Duplicate and then comment or uncomment [count] lines.
+
+{Visual}gcd             Duplicate and then comment or uncomment the highlighted
+                        lines.
+
 The |User| CommentaryPost autocommand fires after a successful operation and
 can be used for advanced customization.
 

plugin/commentary.vim

@@ -121,4 +121,54 @@ if !hasmapto('<Plug>Commentary') || maparg('gc','n') ==# ''
   nmap gcu <Plug>Commentary<Plug>Commentary
 endif
 
+if !get(g:, "commentary_disable_dupe_and_comment_mappings", 0)
+
+    function! s:setcommentaryreg(reg)
+    let s:targetreg = a:reg
+    endfunction
+
+    function! s:yankandcomment(type,...)
+    " only linewise operations make sense (to me, at least)
+    " so I am ignoring `type`
+    if a:0
+        let [mark1, mark2] = [a:type, a:1]
+        let reg = a:2
+    else
+        let [mark1, mark2] = ["'[", "']"]
+        let reg = get(s:, "targetreg", '"')
+    endif
+    execute 'normal! ' . mark1 . '"' . reg . 'y' . mark2 . ']'
+    call <SID>go(line(mark1),line(mark2))
+    execute 'normal! ' . mark1
+    endfunction
+
+    function! s:yankcommentpaste(type,...)
+    if a:0
+        let [mark1, mark2] = [a:type, a:1]
+    else
+        let [mark1, mark2] = ["'[", "']"]
+    endif
+    let savereg = @"
+    execute "normal " . mark1 ."gcy" . mark2 . "]"
+    execute "normal! " . mark2 . "p" . mark1
+    let @" = savereg
+    endfunction
+
+    xnoremap <silent> <Plug>CommentaryYank     :<C-U>call<SID>yankandcomment("'<", "'>", v:register)<CR>
+    nnoremap <silent> <Plug>CommentaryYank     :<C-U>call <SID>setcommentaryreg(v:register)<CR>:set opfunc=<SID>yankandcomment<CR>g@
+    nnoremap <silent> <Plug>CommentaryYankLine :<C-U>call <SID>setcommentaryreg(v:register)<CR>:set opfunc=<SID>yankandcomment<Bar>exe 'norm! 'v:count1.'g@_'<CR>
+    xnoremap <silent> <Plug>CommentaryDupe     :<C-U>call<SID>yankcommentpaste("'<", "'>", v:register)<CR>:normal! '>j<CR>
+    nnoremap <silent> <Plug>CommentaryDupe     :<C-U>call <SID>setcommentaryreg(v:register)<CR>:set opfunc=<SID>yankcommentpaste<CR>g@
+    nnoremap <silent> <Plug>CommentaryDupeLine :<C-U>call <SID>setcommentaryreg(v:register)<CR>:set opfunc=<SID>yankcommentpaste<Bar>exe 'norm! 'v:count1.'g@_'<CR>
+    xnoremap <silent> <Plug>Commentary     :<C-U>call <SID>go(line("'<"),line("'>"))<CR>
+
+    xmap gcy   <Plug>CommentaryYank
+    nmap gcy   <Plug>CommentaryYank
+    nmap gcyy  <Plug>CommentaryYankLine
+    xmap gcd   <Plug>CommentaryDupe
+    nmap gcd   <Plug>CommentaryDupe
+    nmap gcdd  <Plug>CommentaryDupeLine
+
+endif
+
 " vim:set et sw=2: