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Bug introduced in V10 and partially fixed in V11.1.1

TLDR

Various of expressions which have fancy typeset form or are designed as UI elements won't survive ToExpression @* ToBoxes round-trip. And they should.

Examples

  • InterpolatingFunction (new)

    MakeExpression[#, StandardForm] & @ ToBoxes @ Interpolation[
    {{0, 0}, {1, 1}, {2, 3}, {3, 4}, {4, 3}, {5, 0}}
] // Shallow

    ErrorBox[ErrorBox[TagBox[<<5>>]]]

    ToExpression::esntx: Could not parse TagBox[<<1>>] as input.

  • InputField

    ToExpression @ ToBoxes @ InputField[Dynamic[x]]

     $Failed

    ToExpression::notstrbox: InputFieldBox[x] is not a string or a box. ToExpression can only interpret strings or boxes as Wolfram Language input.

    I don't expect InputField[Dynamic[x]] but at least something which is a proper expression, e.g. button works:

    ToExpression @ ToBoxes @ Button[Dynamic[x]] // InputForm

    Button[Dynamic[x], Evaluator -> None, Appearance -> Automatic, Method -> "Preemptive"]

    Things get weirder, MakeExpression can handle InputField case:

    InputForm @ MakeExpression[
    #,
    StandardForm
] & @ ToBoxes @ InputField[Dynamic[x]]

    HoldComplete[InputField[Dynamic[x]]]

  • FileNameSetter

    InputForm@MakeExpression[
  #,
  StandardForm
] & @ ToBoxes @ FileNameSetter[Dynamic[x]]

    ErrorBox[RowBox[{"FileNameSetterBoxes", "[", ErrorBox[Dynamic[x]], ",", "Open", ",", All, "]"}]]

    Syntax::sntxf: "FileNameSetterBoxes[" cannot be followed by "x,Open,All]".

Question

Are those bugs or have I missed something. Please help me understand that. :)

related

ToExpression and ToBoxes aren't inverses of each other?

How to make RawBoxes to be Expression

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  • 1
    $\begingroup$ x = Dynamic[y]; MakeExpression@MakeBoxes@FileNameSetter[x] and x = Dynamic[y]; ToExpression@MakeBoxes@FileNameSetter[x] do work. $\endgroup$
    – Karsten7
    Sep 5, 2016 at 12:44
  • 1
    $\begingroup$ I think this should be tagged bugs, because MakeExpression@MakeBoxes@FileNameSetter[Dynamic[f]] and ToExpression@ToBoxes@FileNameSetter[Dynamic[f]] works in Mathematica version 9.0.1. $\endgroup$
    – Karsten7
    Sep 5, 2016 at 13:01
  • $\begingroup$ @Karsten7. thanks for checking! I agree but I wanted to ask community. $\endgroup$
    – Kuba ♦
    Sep 5, 2016 at 13:03
  • $\begingroup$ In version 9 ToBoxes@FileNameSetter[Dynamic[f]] creates an InterpretationBox. Since version 10 a TemplateBox is created. $\endgroup$
    – Karsten7
    Sep 5, 2016 at 13:22
  • 3
    $\begingroup$ @Karsten7. The definition does exist. But it's in the stylesheet. I.e., CurrentValue[{StyleDefinitions, "FileNameSetterBoxes"}]. Which the FE understands, but the kernel does not. So this does properly roundtrip to output cells and back to input cells, but not through the more constrained MakeBoxes/MakeExpression roundtrip. $\endgroup$
    – John Fultz
    Sep 7, 2016 at 13:52

1 Answer 1

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A support case with the identification [CASE:3706792] was created.

  • InputField

    [...] This is an issue with ToExpression. I have brought it to the attention the relevant developers and they are further investigating the issue. [...]

    Bug introduced in V10 and persisting through V11.1.1

  • FileNameSetter

    [...] the issue for FileNameSetter is different than in the other cases [...]

    Bug introduced in V10 and fixed V11.1.1

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