Get what object a button belongs to?

xkrja

I will try to shorten this question. If I have the following class:

public class MyClass
{
public int MyInt {get; set;}
public Button MyBtn {get; set;}
}

Now, let's say I have a for-loop that generates several objects of this class and hooks it up to an event handler like this:

for (int i = 0; i < 5; i++)
{
MyClass myClass = new MyClass();
myClass.MyInt = i;
myClass.MyBtn = new Button();
myClass.MyBtn.Click += (s, e) =>
{
//Is it possible to get the value of 'myClass.MyInt'
//in this event handler since 'myClass.MyBtn' belongs
//to the same object?
};
}

So, my question is: Is it possible to get the value of 'myClass.MyInt' when the button is clicked? I mean, 'myClass.MyBtn' and 'myClass.MyInt' belongs to the same object. The problem is that I must hook up all buttons to the same event handler. Thanks for help!

Pete OHanlon

If you look at the method declaration for your event handler, you'll see a parameter called s of type object - by convention, this is the object that raised the event. So, all you need do is cast s to Button as in:

Button button = s as Button;
if (button != null)
{
// Do something...
}

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Lost User

Yes. There are 5 MyClass instances and you can use one method for all events. This is better :

private List<MyButton> myButtons = new List<MyButton>();
private void CreateButtons()
{
for(int i = 0; i < 5; i++)
{
MyButton myButton = new MyButton();
myButton.MyInt = i;
myButton.Click += new EventHandler(myButton_Click);
myButtons.Add(myButton);
}
}

private void myButton_Click(object sender, EventArgs e)
{
MyButton myButton = sender as MyButton;
if(myButton != null)
{
MessageBox.Show(myButton.MyInt.ToString());
}
}

public class MyButton : Button
{
private int myInt;

public int MyInt
{
get { return myInt; }
set { myInt = value; }
}
}

xkrja

Thanks for the reply. Yes, I know I can get the object that raised that event. But that object belongs to an object 'myClass' which in turn contains 'myClass.MyInt'. Is it possible to get which of the 'myClass.MyBtn' that raised the event. If I can get that I would also be able to read out the value of 'myClass.MyInt'

xkrja

Thanks for the reply! I think that was exactly what I was looking for. I'll try to implement this in my real case and I get back if I don't succeed.

Luc Pattyn

You don't even need an extra class, you could store the MyClass reference inside the Button using myClass.MyBtn.Tag=myClass; so later an event handler could convert its sender to Button to MyClass instance. :)

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Daniel Grunwald

xkrja wrote:

//Is it possible to get the value of 'myClass.MyInt' //in this event handler since 'myClass.MyBtn' belongs //to the same object?

In your example code: yes. Just use myClass.MyInt. The lambda expression will capture the myClass variable, so every event handler will know to which MyClass instance it belongs. You should not capture the i variable - that would always be 5 because the loop has terminated when the event executes. But capturing variables declared inside the loop will give you the value from the corresponding iteration.