如何将额外的参数传递给事件处理程序？

Question

I am trying to call a shared global event handler from my form's button click event.

public void button21_Click(object me, EventArgs MyArgs) {
  button17_Click(me, MyArgs);  /// WORKS!
}

What I want to do is pass in my XML to the method.

Something like:

public void button21_Click(object me, EventArgs MyArgs) {
  button17_Click(me, MyArgs, MyXmlString);  /// ERROR!
}

I do not always need XML in the button17_Click() method, only when button21 is pressed.

How can I do this?

Answer 1

You don't pass XML (or other arbitrary data types) to event handlers in .NET. They have a particular signature, and that's what you have to use.

You should not be calling button17_click from button21_click. Instead, try this:

public void button17_Click(object sender, EventArgs e)
{
    CommonFunctionality();
}

public void button21_Click(object sender, EventArgs e)
{
    CommonFunctionality();
}

private void CommonFunctionality()
{
    // In here, place the code that used to be in button17_click
}

You may then need to create a version of the common functionality that can use your XML.

Answer 2

I would not try to call your event handler directly, leave that up to the events themselves.

What you should do instead is move the logic for button17 into a separate method and call that method instead.

private void button17_Click(object sender, EventArgs e)
{
    // call the newly created method instead (with the XML argument null)
    HandleClickOperation(null);
}

private void button21_Click(object sender, EventArgs e)
{
    // call the newly created method instead (with the XML argument set)
    HandleClickOperation(MyXmlString);
}

private void HandleClickOperation(string xmlString)
{
    if (xmlString == null)
    {
        // do things unique to button17 behavior
    }
    else
    {
        // do things unique to button21 behavior
    }
    // the logic that was in button17_Click()
}

Answer 3

OK, this question is a little better than yesterday, bu we still can't see :

• what is the declaration of button17_Click
• why is button17_Click an eventhandler?
• why is it a 'global' eventhandler ?
• what do you mean by 'global' here?
• is it your code (can you change button17_Click) ?
• ...

And all that is needed to form an answer or an advice.