Autoupdate Dynamic Variable and Selectable

Question

Does there exist a technique to construct a Cell that allows you to both auto update a Dynamic variable and allows you select the code while the variable is being updated?

For example

Generated from the following code

a = 0;
task = CreateScheduledTask[
   a = a + 1
   , 1];
StartScheduledTask[task];
Print@Button["RemoveScheduleTask", RemoveScheduledTask[task]];
InputField[Dynamic[a], Number]
Dynamic[a]

Now if I select 100 in the InputField my selection gets unhighlighted as soon as the variable gets updated, meaning I don't get enough time to edit the variable.

Now if I select the 100 in the second Cell and attempt to change the value nothing changes because of the nature of how Mathematica works.

The data I am working with is multiline so I would prefer if there was some way to modify the Cell output so that I could update the variable while the scheduled task runs in the background. The above is a simplified issue of the issue, but illustrates the functionality quiet clearly.

Question: How do I update a varaible's value if is constantly being updated?

Answer 1

I've done some work on this problem. What I've done addresses the issues raised by the toy example presented in the question. Whether or not it can contribute to the OP's real problem is something only he can decide.

Evaluating update brings up a input dialog which will accept a number from the user. It rounds the number to an integer and then binds the global variable count to the integer.

update[] := (
  count = 
    DialogInput[{val = count},
      Column[{
        Row[{Style["Enter an integer", "Helvetica", 12]}],
        InputField[Dynamic@val, Number],
        Button["OK", DialogReturn[Round@val]]
      }]
    ]
  )

The following code block does the following:

• initializes count

• starts a task which incements count in the background

• creates two buttons: one to bring up the input dialog; a second to stop and destroy the background task

.

count = 0;
StartScheduledTask[CreateScheduledTask[++count, 1]];
Column[{
  Button["Update count", update[], Method -> "Queued"],
  Button["Remove Task", RemoveScheduledTask[First@ScheduledTasks[]]]}]

And finally a cell for watching the count.

Dynamic[count]

This code appears to be stable and reliable, mainly because when the dialog appears, the background task stops and waits for dialog to be dismissed. Therefore, race conditions are avoided.