SharePoint 2010 error: site master page setting currently applied to this site is invalid

Ugh, Sharepoint 2010. ANYWAY. If you see this error "site master page setting currently applied to this site is invalid" it's probably cos you need to do the following things:

- Set the UI Compatibility Mode of the MasterPage to 4
- Check in the MasterPage
- Publish the MasterPage

That first bit foxed me. To do this, you have to:

- Site Actions > Site Settings
- Galleries > Master pages and page layouts
- Find your master page, click on it and choose "Edit Properties" from the ribbon
- UI Version > 4

Phun. Is this working for you? Let me know! COMMENT! NO REGISTRATION REQUIRED!

C# delegate reminder

I can't be the only person who forgets how to set up a multicast delegate handler EVERY SINGLE TIME I need one. I guess it just feels messy the way you have to declare the delegate, then create an instance of it, then hook up methods to it, then create an invocation method to call the InvocationList....

Anyway, here's a cheat sheet for a typical ASP.NET page or control implementing a multicast delegate, primarily for myself, but may help someone else, who knows....

    public delegate void MyDelegateDef();
    public MyDelegateDef MyDelegateInstance = null;
    readonly object invocationLock = new object();

    private void InvokeMyDelegateInstance()
    {
        MyDelegateDef handler;
        lock (invocationLock) // Lock to get a thread-safe reference
        {
            handler = MyDelegateInstance;
        }

        if (handler != null)
        {
            foreach (MyDelegateDef delegateMethod in handler.GetInvocationList())
                delegateMethod();
        }
    }

    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);

        // Run methods that are hooked up to MyDelegateInstance by this point
        InvokeMyDelegateInstance(); 
    }

Then anything that needs to hook up to the delegate does it like so (assumes the delegate is declared in an object instance called myControlInstance):

    private void onDelegateEvent()
    {
        // Do your stuff here
    }

    protected override void OnInit(EventArgs e)
    {
        base.OnInit(e);

        // Registers onDelegateEvent() to be called when MyDelegateInstance is invoked
        myControlInstance.MyDelegateInstance += onDelegateEvent;
    }

Okay, so EventHandlers should probably be used in this ASP.NET scenario rather than pure delegates, but the principal is sound!

Incidentally, Jon Skeet is the master at this stuff and you should probably read this and then buy his book.