Question

This may seem totally unreasonable to ask, but I have been designing a multi-panel, real device simulator, that has many different screens and my current approach is to add all the screen objects from the code only and dispose them when I switch to another screen.

I have some fixed objects, that are the real device buttons that are already defined and in place. The thing is, I am separating each panel construction in methods, for example: buildLogin(), buildMainScreen(), etc, and I need to edit some of the screen objects from those methods, like changing the color of an enabled function label to green if enabled or white if disabled.

My question is: would it be possible to declare an object from a method that would be accessible in the whole class, like if it were defined in the variable declaration section? It would be something like the GLOBAL in PHP.

I can’t declare it on top of everything like they would always be because when I dispose the objects, I can’t “re-create” them, because of parenting, or re-using a disposed object or something…

[EDIT] Sample code:

public partial class frmMain : Form
{
    //I could as well do this:
    //Button button1 = new Button();

    public frmMain()
    {
         buildLogin();
    }

    private void buildLogin()
    {
        Panel panel1 = new Panel();
        Controls.Add(panel1);

        //But then, there is no way to do this:
        // if (button1.IsDisposed == true) //because of the panel, or smthing
        Button button1 = new Button();
        panel1.Controls.Add(button1);

        button1.Click += (s, f) => { panel1.Dispose(); buildMainMenu(); };
    }

    private void buildMainMenu()
    {
        Panel panel2 = new Panel();
        Controls.Add(panel2);

        Button button2 = new Button();
        panel2.Controls.Add(button2);
    }

    //This was created from the Designer and is class-scoped
    private void btn_Frame_TSK1_Click(object sender, EventArgs e)
    {
        //Here, I have no access to the objets I've created programatically.
        //button1.Text = "Text changed!";
    }
}

Answer 1

If you want to make sure things are always completely dynamic and always done in the code behind, you may want to look at searching for the controls you’ve created in the Controls collection.

For example, make sure to give button1 an ID value (button1.ID=”textUpdatedButton”) that will identify it uniquely from other controls you create. Then use FindControl or search on the Controls collection to find the control with the ID you want to locate in your event handler.

//This was created from the Designer and is class-scoped
private void btn_Frame_TSK1_Click(object sender, EventArgs e)
{
    Control control = this.FindControl("textUpdatedButton");
    if(control != null && control is Button){
        Button button1 = (Button)control;
        button1.Text = "Text changed!";
    }
}

Alternatively, to make things look more like a variable, you can use a Property to hide the control finding (as mentioned previously):

private Button Button1 {
    get { return (Button)this.FindControl("textUpdatedButton"); }
}

//This was created from the Designer and is class-scoped
private void btn_Frame_TSK1_Click(object sender, EventArgs e)
{
    if(this.Button1 != null){
        this.Button1.Text = "Text changed!";
    }
}

The actual implementation will vary with how you build up your controls, but essentially this approach can let you build everything dynamically in your code behind if you need to do it that way. Just remember to use identifiers to let you find things later.