Programmatically copy code so that all output is commented out

Question

UPDATE: The final palette has a new home here! Please test and provide feedback (usability, suggestions, bugs)

A note to the readers and voters: This is intended for community use, so please test the palettes in practice! I encourage all answerers to "steal" from each others, and come up with a solution that is the most pleasant / practical to use.

---

Sjoerd suggested that when we want to post input lines that alternate with output lines, instead of including the In/Out labels, we could simply comment out the output.

Read his suggestion here:

• How should I include code samples in posts?

I have seen several people use this style in the past few days. The only problem with it that it requires a lot of manual editing (too much work for my taste).

How can we automate this process?

The challenge is:

Create a palette button that will copy the selection in the format suggested by Sjoerd. Two-dimensional expressions (i.e. things like $\int x^2 \; dx$) should be converted to plain text or input form. The notebook contents must not be modified/destroyed.

An example (directly copied from Sjoerd's post):

In[108]:= D[Cos[x] Exp[x], x]
Out[108]= E^x Cos[x] - E^x Sin[x]

should be copied as

D[Cos[x] Exp[x], x]

(*  
===> E^x Cos[x] - E^x Sin[x]
*)

Let us ignore cells that are neither input nor output for now (text, headings, etc.)

Can we create a tool that is good enough to be of practical use to the community?

Answer 1

This is inspired by Rolfs answer, but uses the "Copy As Input" functionality as the starting point. My impression is that using that approach will keep more of the original formatting (concerning linebreaks) but it still isn't perfect in that concern. To see the problems, I didn't change what it does to the its own code (it added some empty lines).

Other differences are that it will look at the current selection instead of using all the content of the selected notebook. And it adds the spaces at the begining of each line so it will directly be recognized as code when pasted into the edit window.

It can't handle correctly anything except input and output cells that have an In/Out tag, otherwise the splitting in input and output cells will not work (although I think it will create something that's not completely useless in those cases...).

CreatePalette[
 Tooltip[
  Button[
   "Copy for MSE",
   FrontEndTokenExecute[SelectedNotebook[], "CopySpecial", 
    "InputText"];
   Map[
    CreateDocument[TextCell[#, "Text", FontFamily -> "Courier"]] &,
    Cases[
     NotebookGet[ClipboardNotebook[]],
     Cell[c_String, ___] :> "    " <> StringReplace[
        StringJoin[Riffle[
          StringReplace[

           StringTrim[
            StringSplit[
             c, ("In" | "Out") ~~ "[" ~~ DigitCharacter .. ~~ "]"]], {

            StartOfString ~~ ":=" ~~ WhitespaceCharacter ~~ input__ :>
              input,

            StartOfString ~~ "=" ~~ WhitespaceCharacter ~~ output__ :>
              "(*\n==> " <> output <> "\n*)"
            }
           ],
          "\n\n"
          ]],
        "\n" -> "\n    "
        ],
     Infinity
     ]
    ],
   Method -> "Queued"
   ],
  "Copy formatted for use in MSE"
  ],
   Saveable -> False
 ]

Answer 2

Copied from applying the palette on its own source code (kind of self-referential button -:) ):

CreatePalette[
  {"Copy In/Out as String", 
   Button["Select Notebook and click", 
      (SelectionMove[CreateDocument[#1], All, Notebook] & )
         [StringJoin @@ 
            Riffle[
              Select[
                Partition[
                  Cases[
                    NotebookGet[SelectedNotebook[]], 
                    Cell[_, "Input", ___] | Cell[_, "Output", ___], -1 
                  ], 2
                ], 
                MatchQ[#1, {Cell[_, "Input", ___], Cell[_, "Output", ___]}] & 
             ] /. 
              {Cell[a_, "Input", ___], Cell[b_, "Output", ___]} :> 
                StringJoin[
                  (StringJoin[
                    (StringTake[#1, {6, -2}] &)
                       [ToString[InputForm[ToExpression[a, StandardForm,Hold]]]],
                       "\n\n(*\n==> ", StringTake[#1, {6, -2}]] & 
                    )[ToString[
                        InputForm[ToExpression[ b, StandardForm, Hold] ]
                      ]
                    ], 
                    "\n*)\n"
                  ], 
          "\n"]]]}]

(*
==> NotebookObject[FrontEndObject[LinkObject["jtc_shm", 1, 1]], 48]
*)