Question

I’m learning C# and what I need is to access control on a Form from other class (the same namespace).

I know there is a lot of posts on this topic here but didn’t find complete solution ‘for dumbs’ so I write here what I figured out and please tell me – is this the correct way ?

Background: I have some ‘debugging’ form in my app and I need all other forms to be able to log their activity into this form. There is some ListBox control where all the logs from other forms are written. When I (or one of my tester-friends without Visual Studio) play around with app and something bad happens, I can look on that debug-form to see all detailed logs what happened just before that ‘moment of error‘.

My main form of the app (frmMain):

namespace myNamespace {

public partial class frmMain : Form {

private frmDebug debug;  // frmDebug is declared in other class
                         // we will hold reference to frmDebug form in 'debug'

public frmMain() {         // constructor of the main form 'frmMain'
  InitializeComponent();
  debug = new frmDebug();  // we create new instance of frmDebug immediately when
}                          // our main form is created (app started) and whole time
                           // of running this app we can access frmDebug from
                           // within frmMain through 'debug' variable


// clicking button 'btnLoggingTest', the log is written 
// in the 'frmDebug' form even if it is closed (not visible)
private void btnLoggingTest_Click(object sender, EventArgs e) {
  debug.Log("log this text for me please");
}

// Click handler of the button 'btnShowDebug' :
private void btnShowDebug_Click(object sender, EventArgs e) {
  debug.ShowDialog();    // here we can show frmDebug (in 'modal' style)
}                        // just to see what log-information is written there


} // frmMain class

} // namespace

And here is the code of class frmDebug itself :
(there is only one Listbox placed on the form)

namespace myNamespace {
public partial class frmDebug : Form {

public frmDebug() {
  InitializeComponent();
}

public void Log(string txt) {    // this is the actual 'Log' function (or method)
  this.listBox1.Items.Add(txt);
  Application.DoEvents();        // if the logging takes place in some 
}                                // computing-intensive 'loop' or function,
                                 // (or in my case FTP login and upload process)
                                 // 'DoEvents' ensures every log appears immediately
                                 // after the 'Log()' was called. Otherwise all logs
                                 // would appear together at once, as soon as the 
                                 // computing-intensive 'loop' is finished

} // class frmDebug

} // namespace

I have a strange feeling in my stomach I’m doing it all wrong so please tell me how to do it properly 🙂
If it’s OK, hope it helps somebody like me.

Thank you !

Answer 1

Your application has probably a class called “Program”. There you will find the code

var mainForm = new frmMain();
Application.Run(frmMain);

Create a static property for the debugging form in this class

public static frmDebug DebuggingForm { get; private set; }

Change the startup code like this

DebuggingForm = new frmDebug();
var mainForm = new frmMain();
Application.Run(frmMain);

From other classes you can access this form like this

Program.DebuggingForm.Log("log this text for me please");         
Program.DebuggingForm.Show();