Want actual cell data from CellEvaluationFunction

Question

Let's say I print a cell like so.

CellPrint@Cell[
  BoxData[" "], "Input", Evaluatable -> True, 
  CellEvaluationFunction -> Function[Print[#];]
  ]

Now I type in several lines of text in the Cell in Mathematica.

For example

I hit Shift+Enter and get the following output.

BoxData[List["1","3"]]

But when I do Ctrl+Shift+e, the Cells content is really

BoxData[
  RowBox[{" ", 
     RowBox[{
       "1", "\[IndentingNewLine]", "\[IndentingNewLine]", "3"}]}]]

Why doesn't CellEvaluationFuction receive the actual cell data? Is there a hidden function/argument that might give me such information?

According to the docs, "CellEvaluationFunction is applied to the BoxData expression representing the input to be evaluated." [Emphasis mine.] The docs do not say that the Front End won't substitute some simplification of the expression in the cell. I believe for TagBox and InterpretationBox, the difference might be quite a bit different. At the least, one should not be surprised that any "typesetting" differences are stripped. — Michael E2, Aug 01 '13 at 23:34
@MichaelE2 Okay then a workaround would be appreciated to achieve such functionality. I am working on a workaround using CellTags right now, but I have some doubts on how dependable it will be with multiple cells. — William, Aug 01 '13 at 23:37
Related: (13317) -- UndocumentedTestFEParserPacket[string, False] would give the unmodified Box form for that string. This is not directly applicable but it may be useful at some point. — Mr.Wizard, Aug 06 '13 at 07:31

score 6 · Accepted Answer · answered Aug 01 '13 at 23:52

6

Make your CellEvaluationFunction this:

Function[Print[NotebookRead[EvaluationCell[]]];]

Note that EvaluationCell (and the CellObject it creates) are new to version 9.

answered Aug 01 '13 at 23:52

John Fultz

John, would you please take a look at my question here? Also, can this answer be made to work in v7 by using SelectionMove and EvaluationCell? – Mr.Wizard Aug 06 '13 at 07:34
@Mr.Wizard I don't have version 7 to test but I willing to be this works in v7 also. Basically I just read the entire notebook and extract the needed Cell. You could probably use CellIds in replacement of CellTags. http://pastebin.com/FmCEPju6 – William Aug 06 '13 at 15:31
@Mr.Wizard The use of EvaluationCell as a selector for SelectionMove, while no longer supported in v9, still seems to work, and also works in older versions. E.g., SelectionMove[EvaluationNotebook[], All, EvaluationCell] – John Fultz Aug 06 '13 at 16:25
@JohnFultz Sorry for the confusion I was talking about my linked code. http://pastebin.com/FmCEPju6 I was responding to Mr.Wizard's comment. It doesn't use EvaluationCell but NoteebokRead[InputNotebook[]] – William Aug 06 '13 at 16:26
@Liam Actually, my comment was confused and didn't make much sense. SE wouldn't let me edit it anymore, so I just deleted it. – John Fultz Aug 06 '13 at 16:28

1 Answers1