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variable definitions - Can I create a dynamic number of rows in TabView through an iteration?


I have written code, with the help of stackoverflow of course, and I want to make it user friendly so that other people in my lab can use it. I'm playing with DialogCreate and similar functions. I want to do something like this so far:


   CreateDialog[TabView[{
   "General" ->
    Column[{
      Row[{TextCell["Project Name:"], InputField[Dynamic[Project]]}],
      Row[{TextCell["Number of Wells:"], InputField[Dynamic[num]], 
        Button["Set", DialogReturn[num]]}]}],
   "Row Selection" ->
    Column[{Do[

      Row[TextCell["Well " <> ToString[i] <> ":"], 
      FileNameSetter[Dynamic[Evaluate[Symbol["w" <> ToString[i]]]], 
     "Open"]], {i, 1, num}]}]}, ControlPlacement -> Left]
 ]

I want to dynamically create more rows based on the input of "Number of Wells" within the same dialogbox but in a different tab. Is anything like this possible or some sort of alternative?



Answer



CreateDialog[
  TabView[
   {"General" -> 

     Column[{Row[{"Project Name:", InputField[Dynamic[project]]}],
        Row[{"Number Of Wells:", InputField[Dynamic[num]], 
        Button["Set", DialogReturn[num]]}]}], 
   "Row Selection" -> 
     Dynamic@Column[
      Table[Row[{"Well " <> ToString[i] <> ":", 
         FileNameSetter[Dynamic[Evaluate[Symbol["w" <> ToString[i]]]],
            "Open"]}], {i, 1, num}]]}, 
   ControlPlacement -> Left]]


enter image description here


Update: There are two problems in the original code:


First, regarding the use of Do, unless an explicit Return is used, the value returned by Do is Null. Please see the docs on Do and the tutorial Loops and control structures. For example


 t = 2; Do[t = 1 + k t, {k, 1, 2}]

does the calculation to change the value of t but does not return anything. You need to explicitly call the new value of t to see the effect of what happened inside Do:


t = 2; Do[t = 1 + k t, {k, 1, 2}];t
(* which gives the result: 7 *)

So, to get your code working with Do, you need to do something like:



"Row Selection" -> 
  Dynamic@Column[tt = {};
  Do[AppendTo[tt, Row[{"Well " <> ToString[i] <> ":",
   FileNameSetter[Dynamic[Evaluate[Symbol["w" <> ToString[i]]]], 
    "Open"]}]],
   {i, 1, num}]; tt]

which, of course, is not as clean as the alternative with Table[...].


Second, regarding why Dynamic[Column[ ...]] is needed please see the tutorial Introduction to Dynamic, in particular, the section Where Should Dynamic Be Placed in an Expression?


By the way, @ is short form of Prefix, and f@x is an alternative syntax for f[x], that is, Dynamic@Column[.....] is the same as Dynamic[Column[...]].



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