CODEWITHSUNDEEP
c#.netvisual-studio-2010
Uğur Gümüşhan
Uğur Gümüşhan

Reputation: 2543

Can I pass values to an event handling function?

I would Like to use a function with parameters on the properties box with event list. this even list box on the right int he visual studio only allows some functions with object sender and eventargs e, and doesn't show a custom function with parameters. Is this a general behavior or should I look for an error?

Upvotes: 0

Views: 116

Answers (5)

Kemal Taskin
Kemal Taskin

Reputation: 545

You can simply use the CommandArgument of your button.

yourButton.Click += new EventHandler(yourButton_Click); yourButton.CommandArgument = "your parameters";

and in the event handler method do the following:

string yourParameters = (sender as Button).CommandArgument.ToString()

Hope this helps.

Upvotes: 1

ken2k
ken2k

Reputation: 48975

The correct way of using events in .Net is the following:

  • use a delegate with a name that ends with EventHandler
  • this delegate with have exactly two parameters, sender and e. sender must be of type object and should contain a reference to the instance of the class that raised the event. e must be of a type that inherits from EventArgs (often EventArgs itself). e is the instance that contains the event data.

You must not expect to find any other event handler signature, it's always (object sender, XXXEventArgs e).

Note that when you raise events and do not need to pass event data, EventArgs.Empty should be used.

public delegate void MyEventHandler(object sender, EventArgs e);

public event MyEventHandler MyEvent;

public void OnMyEvent()
{
    if (this.MyEvent != null)
    {
        this.MyEvent(this, EventArgs.Empty);
    }
}

Upvotes: 0

fixagon
fixagon

Reputation: 5566

you can only register handlers on an event which correspond to the event declaration (delegate signature).

If you want to use predefined event and dont create your own you have to follow the event handler signature

Upvotes: 0

MethodMan
MethodMan

Reputation: 18843

Button.Click is defined as it is, and there is no way to change it. However,

yourButton.Click += delegate { YourButton_click(1); }

will do the job.

Upvotes: 0

Tony Hopkinson
Tony Hopkinson

Reputation: 20320

Write a descendant of EventArgs.

e.g.

public class MyEventArgs: EventArgs {
    public MyEventArgs(string arg1, int arg2) {
        this.MyValue = arg1;
        this.MyNumber = arg2;
    }

    public string MyValue;
    public int MyNumber;

}

Nows it's an okay parameter for an EventHandler, when you write one e, will have MyValue and MyNumber properties.

Upvotes: 1

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