How can I pass addition local object variable to my event handler?

Question

I want to a pass local object to the event handler. How can I do that? For example, how can I reference the "graphic" object, which is declared in the main function below, in the event handler function "hyperlinkButton_Click"?

    void main()
    {
        Graphic graphic = new Graphic();

        hyperlinkButton.Click+=new RoutedEventHandler(hyperlinkButton_Click);
    }

    void hyperlinkButton_Click(object sender, EventArgs e)
    {

    }

score 11 · Accepted Answer · answered Apr 13 '11 at 16:34

11

Use a delegate or a lambda expression.

hyperlinkButton.Click += (sender, e) => HandleGraphic(graphic, sender, e);

answered Apr 13 '11 at 16:34

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score 1 · Answer 2 · answered Apr 13 '11 at 16:34

You could try closing on the graphic variable:

void main()
{
    Graphic graphic = new Graphic();

    hyperlinkButton.Click += (sender, e) => 
    {
        graphic.Blah(); 
    };
}

This would not be a good idea if you eventually need to remove the event handler manually. Alternatively, you could make graphic a field instead of a local variable.

score 1 · Answer 3 · answered Apr 13 '11 at 19:38

   void main()
    {
        Graphic graphic = new Graphic();
        hyperlinkButton.Tag = graphic;
        hyperlinkButton.Click+=new RoutedEventHandler(hyperlinkButton_Click);
    }

    void hyperlinkButton_Click(object sender, EventArgs e)
    {
       Graphic graphic =(sender as HyperlinkButton).Tag as Graphic;
    }

but not good way.

How can I pass addition local object variable to my event handler?

3 Answers3

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