Question

I’ve created a small sample project to try to understand events. I want to eventually implement these types of events in my future projects especially when passing data from child form to parent form … which is what I do a lot. I’ve been told the best way to do this, to avoid coupling, is to use events.

Is my code below the correct/conventional way to achieve this?

// Subscriber
public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        registerUserAccount registerAccount = new registerUserAccount();
        registerAccount.onAccountCreated += onAccountRegister;
        registerAccount.registerAccount();
    }

    public void onAccountRegister(object sender, AccountCreatedEventArgs e)
    {
        MessageBox.Show(e.username + " - " + e.password);
    }
}

public delegate void accountCreatedEventHandler(object sender, AccountCreatedEventArgs e);

// Publisher
public class registerUserAccount
{
    public event accountCreatedEventHandler onAccountCreated;

    public registerUserAccount()
    {

    }

    public void registerAccount()
    {
        // Register account code would go here

        AccountCreatedEventArgs e = new AccountCreatedEventArgs("user93248", "0Po8*(Sj4");
        onAccountCreated(this, e);
    }    
}

// Custom Event Args
public class AccountCreatedEventArgs : EventArgs
{
    public String username;
    public String password;

    public AccountCreatedEventArgs(String _username, String _password)
    {
        this.username = _username;
        this.password = _password;
    }
}

Note: The code above is placed in the same namespace for demonstration and testing only.

A couple of questions too:

1) I tried to have the registerUserAccount constructor call the registerAccount method, but for some reason it wasn’t giving me the message box. I assume this is because the registerAccount method is called before the the class subscribes to listen to the event?

2) I tried to use methods in the EventArgs class, but it wasn’t allowing me to call the public methods. Is it convention to access the properties like I have?

Thanks

Answer 1

1) Message box was not called because you are subscribing to event after the instantiation of the class so method onAccountRegister() will not be called

registerUserAccount registerAccount = new registerUserAccount();
registerAccount.onAccountCreated += onAccountRegister; 

BTW,

I would suggest renaming of event and event handler method:

• onAccountCreated to AccountCreated
• onAccountRegister to AccountCreatedHandler since you’re subscribing to AccountCreated event not AccountRegister