Accessing non-deterministic functions in UDF

For those who didn't know, the following function definition will throw an error in SQL Server 2000.

create function fn1()
returns datetime
as
begin
return getdate()
end

The error thrown is "Invalid use of 'getdate' within a function".

Thats because built in non deterministic functions cannot be used inside UDF. Well there is a work around for this.

Lets create a view like this:

create view curdate
as
select getdate() as dt

And create a function this way.

create function fn1()
returns datetime
as
begin
return (select dt from curdate)
end

Now calling the function will get me the current date.

But, calling getdate() directly in an UDF in SQL Server 2005 doesn't throw any error. Meaning, the function definition given in the beginning of this post will actually work fine in SQL Server 2005.

Now, the question is why couldn't you call built-in non deterministic function inside your UDF in SQL Server 2000 and why was it allowed now?

But then the following function when you try create in SQL Server 2005 throws an error.

create function fn2()
returns float
as
begin
return rand()
end

And the error is "Invalid use of side-effecting or time-dependent operator in 'rand' within a function". The same error is thrown if I try to call newid()

Well, then why was getdate() allowed?

Any idea?