用返回值调用public void和private字符串方法

Question

In my application I want to have my main form(Form1) call a method on my UserControl(EmailControl). Below are the three main methods I am wanting to call:

public void InitializeConnection(string hostname, int port)
    {
        try
        {
            _imapClient = new TcpClient(hostname, port);
            _imapNs = _imapClient.GetStream();
            _imapSw = new StreamWriter(_imapNs);
            _imapSr = new StreamReader(_imapNs);

            label1.Text = "*** Connected ***";
            Response();
        }
        catch (SocketException ex)
        {
            Console.WriteLine(ex.Message);
        }
    }

,

    public void AuthenticateUser(string username, string password)
    {
        _imapSw.WriteLine("$ LOGIN " + username + " " + password);
        _imapSw.Flush();
        label2.Text = "Logged in";
        Response();
    }

and

    public string MailCount()
    {
        _imapSw.WriteLine("$ STATUS INBOX (messages)");
        _imapSw.Flush();

        string res = Response();
        Match m = Regex.Match(res, "[0-9]*[0-9]");
        return m.ToString();
    }

To do this, I am using this on the usercontrol page:

    Form1.getemail += new Form1.sendtoemail(this.sendover);

and

    public void sendover()
    {
        InitializeConnection("hostname", 123);
        AuthenticateUser("username", "password");
        MailCount();
    }

Then on my main page I have

public delegate void sendtoemail(object sender, EventArgs e);
    public event sendtoemail getemail;

and

private void Form1_Load(object sender, EventArgs e)
    {
        if (this.getemail != null) 
        {
            this.getemail(this, e);

        }
    }

After doing this, on my usercontrol page it is telling me that there is no overload for "sendover" matches delegate "sendtoemail", and that I need an object reference. What exactly is throwing the error?

Answer 1

The getemail event is of type sendtoemail , so the function you add as a handler must match that signature.

Here are two solutions:

Change

public void sendover()

to

public void sendover(object sender, EventArgs e)

or change

Form1.getemail += new Form1.sendtoemail(this.sendover);

to

Form1.getemail += (s, e) => sendover();

The first solution changes the signature of sendover to match the delegate type, and the second solution creates an anonymous function with the correct type which calls sendover.

Answer 2

Your method sendover doesn't respect the sendtoemail delegate's method signature:

public delegate void sendtoemail(object sender, EventArgs e); // accepts 2 parameters

Instead of the method declaration:

public void sendover() { // ...

... declare it as...

public void sendover(object sender, EventArgs e) { // ...