Foreach over multiple ControlCollections

Question

I have a tab control in my Windows Form, and I want to iterate over each element in two different tabs. When a file is opened, I want all the elements of both to be enabled, and when the file is closed, all to be disabled.

I have no clue how to accomplish this, however, because the controls aren't in an array or list, but in a ControlsCollection. I asked a second ago about foreach statements and learned a bit about lambda, but I don't know how I can apply it here.

Here's what I have:

List<Control.ControlCollection> panels = new List<Control.ControlCollection>();
panels.Add(superTabControlPanel1.Controls);
panels.Add(superTabControlPanel2.Controls);
foreach(Control.ControlCollection ctrlc in panels){
    foreach (Control ctrl in ctrlc) { 

    }
}

Is this possible with one foreach statement, or somehow simpler?

Answer 1

I would use Linq, with the following:

foreach (var ctrl in panels.SelectMany (x => x.Cast<Control> ())) {
     // Work with the control.
}

The key is to use the Cast extension method on IEnumerable to make it usable with the SelectMany.

Answer 2

Did you know that if you disable a parent control, then all nested controls are disabled too? Simply disabling the two tab panels will disable all children too. Enabling the panel reverts the effect.

I know this doesn't answer your question, but it is a better solution.

Answer 3

I would do something like this:

List<Control> controls = new List<Control>();
controls.AddRange(superTabControlPanel1.Controls.GetControls());
controls.AddRange(superTabControlPanel2.Controls.GetControls());
foreach(Control ctrl in controls){
    //Do something
}

I don't have VS handy at the moment, and not sure if GetControls() exists. But you can use the general idea: instead of collection of panels, have a collection of controls, and iterate through controls in one loop.

Answer 4

I would probably Union the two collections and avoid using a Generic List<T> all together.

var controls = superTabControlPanel1.Controls.Union(superTabControlPanel2.Controls);

foreach (var control in controls) {
  //...
}

Or you could chain multiple collections together.

var controls = 
  (superTabControlPanel1.Controls)
  .Union
  (superTabControlPanel2.Controls)
  .Union
  (superTabControlPanel3.Controls);