Question

I have a problem with adding parameters to EventHandler.
I have a control when user select message and choose to who he want to send it.

I need to handler OnConfirmForwarClosed add in some way variable item.

How can I do it?

private void inboxContextMenu_ItemClick(object sender, Telerik.Windows.RadRoutedEventArgs e)
        {
            var item = (RadMenuItem)e.Source;
            RadWindow.Confirm("Do you want forward this message to item.DataContext.HandlerName ?", OnConfirmForwarClosed);


        }

        private void OnConfirmForwarClosed(object sender, WindowClosedEventArgs e)
        {
            if (e.DialogResult == true)
            {
         //here I need item from caller
            }
        }

EDIT
I need a result which I can get by this solution:

 RadWindow.Confirm("Do you want forward this message to item.DataContext.HandlerName ?",(s,ea)=>
                                         {
                                             if(ea.DialogResult==true)
                                             {
                                                 MessageBox.Show((item.DataContext as Handler).HandlerId.ToString());
                                             }
                                         });

Answer 1

If i understand your question correctly, you don’t want to “lift” the local variable into lambda, such as…

void inboxContextMenu_ItemClick(object sender, Telerik.Windows.RadRoutedEventArgs e) {
    var item = (RadMenuItem)e.Source;
    RadWindow.Confirm(
        "Do you want forward this message to item.DataContext.HandlerName ?",
        (sender, e) => {
            if (e.DialogResult == true) {
                // You can use 'item' here directly.
            }
        }
    );
}

…and instead you want to keep the OnConfirmForwarClosed (presumably to subscribe to events not shown here). If that’s correct, then you have couple of options:

1.

You could just arrange your methods differently:

void inboxContextMenu_ItemClick(object sender, Telerik.Windows.RadRoutedEventArgs e) {
    var item = (RadMenuItem)e.Source;
    RadWindow.Confirm(
        "Do you want forward this message to item.DataContext.HandlerName ?",
        (sender, e) => OnConfirmForwarClosedImp(sender, e, item)
    );
}

void OnConfirmForwarClosedImp(object sender, WindowClosedEventArgs e, RadMenuItem item) {
    if (e.DialogResult == true) {
        if (item != null) {
            // Use 'item'.
        }
        else {
            // OnConfirmForwarClosed was called from somewhere else.
        }
    }
}

void OnConfirmForwarClosed(object sender, WindowClosedEventArgs e) {
    OnConfirmForwarClosedImp(sender, e, null);
}

2.

Set the object field:

void inboxContextMenu_ItemClick(object sender, Telerik.Windows.RadRoutedEventArgs e) {
    item = (RadMenuItem)e.Source;
    try {
        RadWindow.Confirm(
            "Do you want forward this message to item.DataContext.HandlerName ?",
            OnConfirmForwarClosed
        );
    }
    finally {
        item = null;
    }
}

RadMenuItem item = (RadMenuItem)e.Source;

void OnConfirmForwarClosed(object sender, WindowClosedEventArgs e) {
    if (e.DialogResult == true) {
        if (item != null) {
            // Use 'this.item'.
        }
        else {
            // OnConfirmForwarClosed was called from somewhere else.
        }
    }
}

3.

Co-opt one of the existing OnConfirmForwarClosed parameters:

void inboxContextMenu_ItemClick(object sender, Telerik.Windows.RadRoutedEventArgs e) {
    var item = (RadMenuItem)e.Source;
    RadWindow.Confirm(
        "Do you want forward this message to item.DataContext.HandlerName ?",
        (sender, e) => OnConfirmForwarClosed(item, e)
    );
}

void OnConfirmForwarClosed(object sender, WindowClosedEventArgs e) {
    if (e.DialogResult == true) {
        var item = sender as RadMenuItem;
        if (item != null) {
            // Use 'item'.
        }
        else {
            // OnConfirmForwarClosed was called from somewhere else.
        }
    }
}

Etc, etc…