Question

Here’s my extension method for invoke on a control:

public static void Invoke<T>(this T c, Action<System.Windows.Forms.Control> DoWhat)
    where T:System.Windows.Forms.Control
{
    if (c.InvokeRequired)
        c.Invoke(o=> DoWhat(c) );
    else
        DoWhat(c);
}

ds is a strongly typed dataset.
This works:

Action<DataGridView> a = row => row.DataSource = ds.bLog;
this.dataGridView1.Invoke(a);

this doesn’t compile:

this.dataGridView1.Invoke<DataGridView>(o => o.DataSource = ds.bLog);

and says System.Windows.Forms.Control does not contain a definition for ‘DataSource’…

do I really have to break this into 2 lines?
For clarity/safety should I call the generic extension method InvokeSafe?

Edit:Extension method revised (works, but I’d like to remove the named delegate requirement):

private delegate void myDel();

public static void InvokeSafe<T>(this T c, Action<T> DoWhat) where T : Control
{
    myDel d = delegate() { DoWhat(c); };
    if (c.InvokeRequired)
        c.Invoke(d);
    else
        DoWhat(c);
}

I can’t seem to figure out how to make factor out myDel into an anonymous delegate in the block?

Answer 1

Try changing your method signature to:

public static void Invoke<T>(this T c, Action<T> DoWhat)

This will let your Action use the desired type that you specify.