CODEWITHSUNDEEP
c#messagebox
Nuru Salihu
Nuru Salihu

Reputation: 4928

Only assignment, call, increment, decrement, and new object expressions can be used as a statement : Messagebox

This what i am trying to achieved

  if( this.BeginInvoke((Action)(
        () => MessageBox.Show("Test", 
                              MessageBoxButtons.YesNo) == DialogResult.No)))

The above gives error. I try seperating the delegate to an outside method like

delegate void test(string text);
private void SetTest(string text)
{
 if(MessageBox.Show(text,"", MessageBoxButtons.YesNo) == DialogResult.No)

}

But it breach the very reason why i need the delegate. I found out the first works for me but i don't know how to put it in an if/else statement. Pls any help in a better way i can achieve some thing like below would be appreciated.

  if(this.BeginInvoke((Action)(
      () => MessageBox.Show("Test", 
                            MessageBoxButtons.YesNo) == DialogResult.No)))

Upvotes: 1

Views: 2438

Answers (3)

Idle_Mind
Idle_Mind

Reputation: 39122

Another variation....man this is ugly:

if ((bool)this.Invoke((Func<bool>)delegate
  {
  return MessageBox.Show("Test Message", 
                         "Test Title", 
                         MessageBoxButtons.YesNo) == DialogResult.No;
  }))
{
    Console.WriteLine("No was indeed selected.");
}

This should work on any version of C#:

private void button1_Click(object sender, EventArgs e)
{
    System.Threading.Thread T = new System.Threading.Thread(Foo);
    T.Start();
}

delegate bool SetTestDelegate(string text);
private bool SetTest(string text)
{
    return (MessageBox.Show(text, "", MessageBoxButtons.YesNo) == DialogResult.No);
}

private void Foo()
{
    if ((bool)this.Invoke(new SetTestDelegate(SetTest), new object[] {"test"}))
    {
        Console.WriteLine("No was indeed selected.");
    }
}

EDIT: You could refactor that code into something more useful...

private void button1_Click(object sender, EventArgs e)
{
    System.Threading.Thread T = new System.Threading.Thread(Foo);
    T.Start();
}

private void Foo()
{
    if (Response("test") == System.Windows.Forms.DialogResult.No)
    {
        Console.WriteLine("No was indeed selected.");
    }
}

delegate DialogResult ResponseDelegate(string text);
private DialogResult Response(string text)
{
    if (this.InvokeRequired)
    {
        return (DialogResult)this.Invoke(new ResponseDelegate(Response), new object[] { "test" });
    }
    else
    {
        return MessageBox.Show(text, "", MessageBoxButtons.YesNo);
    }
}

Upvotes: 2

max
max

Reputation: 34407

It seems like you need an Invoke() method, not BeginInvoke():

var messageBoxResult = (DialogResult)Invoke(new Func<DialogResult>(
    () => MessageBox.Show("Test", "Test", MessageBoxButtons.YesNo)));
if(messageBoxResult == DialogResult.No)
{
}

BeginInvoke executes delegate asynchronously, meaning that the result is not immediately available on the thread which calls BeginInvoke.

Upvotes: 2

Noctis
Noctis

Reputation: 11763

Why not make your (and your fellow coders) life easier, and do something like:

var user_said_no = this.BeginInvoke((Action)(
   () => MessageBox.Show("Test", MessageBoxButtons.YesNo) == DialogResult.No));

And then have:

if (user_said_no)
   cancel_nuclear_attack() ; // Or whichever things you need to do.

Upvotes: 1

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