calling a event handler within another event handler?

Question

Here is the short sample code:

private void txtbox1_DoubleClick(object sender, EventArgs e)
{
    button1_Click(object sender, EventArgs e); //can I call button1 event handler?
}

private void button1_Click(object sender, EventArgs e)
{
    MessageBox.Show(txtbox1.Text);
}

I wonder if it would be okay to code in the above way?

Solution 1

You can do that - although the code you provide can't be compiled. It should look like this:

private void txtbox1_DoubleClick(object sender, EventArgs e)
{
    button1_Click(sender, e);
}

private void button1_Click(object sender, EventArgs e)
{
    MessageBox.Show(txtbox1.Text);
}

But for best practice and code readability, you're probably better off doing this, especially as you are not making use of sender and e:

private void txtbox1_DoubleClick(object sender, EventArgs e)
{
    ShowMessageBox();
}

private void button1_Click(object sender, EventArgs e)
{
    ShowMessageBox();
}

private void ShowMessageBox()
{
    MessageBox.Show(txtbox1.Text);
}

Solution 2

Yes you can do that; an event handler is just another method.

However it might be worth creating a new method that shows the message box, and having both Click event handlers call that:

private void txtbox1_DoubleClick(object sender, EventArgs e)
{
    ShowTextboxMessage();
}

private void button1_Click(object sender, EventArgs e)
{
    ShowTextboxMessage();
}

private void ShowTextboxMessage()
{
    MessageBox.Show(txtbox1.Text);
}

Solution 3

An event handler is nothing more than a method, so you can call it like any other.

Comments

[woodykiddy]

Hmm looks better in the way you put it. But any "side-effects" if I use nested event handling? I guess it's just more or less a bit confusing.

[George Duckett]

No side-effects, you're just calling a method like any other really.

[woodykiddy]

hmm, are sender and e used in both event handlers referencing the same thing?

[Roy Goode]

@woodykiddy no - the sender for txtbox1_DoubleClick is txtbox1 and the sender for button1_Click will be button1 if the event handlers have been wired as standard using the Windows Form Designer