Using MethodInvoker without Invoke

c#, lambda, multithreading, user-interface

Solution

Nothing's wrong with it... but you can add an extension method to make it all somewhat nicer:

public static void InvokeIfNecessary(this Control control,
                                     MethodInvoker action)
{
    if (control.InvokeRequired)
    {
        control.Invoke(action);
    }
    else
    {
        action();
    }
}

Then you can write:

this.InvokeIfNecessary(() => Label1.Text = "Foobar");

Much neater :)

There is a very slight performance drawback from creating a delegate when you don't need to, but it's almost certainly insignificant - concentrate on writing clean code.

Note that even if you don't want to do that, you can still make your variable declaration simpler in your existing code:

MethodInvoker updateText = () => Label1.Text = "Foobar";

That's one benefit of using a separate variable - you don't need the `new MethodInvoker` bit to tell the lambda expression what type of delegate you want...

Problem

I am writing GUI applications for some time now and one thing I always use are MethodInvoker + lambda functions to do cross-thread access. From the examples I find I always see stuff like this: Version 1 ``` if (InvokeRequired) { Invoke(new MethodInvoker(() => { Label1.Text = "Foobar"; }); } else { Label1.Text = "Foobar"; } ``` However this leads to code-duplication --> major baddie to me. So what's wrong with this? Version 2 ``` MethodInvoker updateText = new MethodInvoker(() => { Label1.Text = "Foobar"; }); if (InvokeRequired) { Invoke(updateText); } else { updateText(); } ``` Now I have the functionality bundled in one variable and call it with Invoke or as a function pointer when appropriate. Is version 2 worse performance-wise? Or is i bad practice to use anonymous functions for this?

Original source