Why can't we make reference variables?

[Namespace]

On Thursday, 30 August 2012 at 07:35:34 UTC, Namespace wrote:
>
>> I had totally forgotten what it says in "The book" about 
>> struct and class construction. It's basically that all fields 
>> are first initialized to either T.init or by using the field's 
>> initializer. That means the use of ref inside class or struct 
>> would be quite restricted:
>>
>> int globalVal;
>>
>> struct MyStruct
>> {
>>    // ref int defaultInitRef; // Illegal: reference variables
>>                               // can't be default initialized
>
> But you can handle it like const members: you have to 
> initialize these members in the ctor.

Furthermore I suggest that with "ref" marked Objects _can't_ be 
null.
So ref Foo fr = null; is equally forbidden as
[code]
Foo f; // same as Foo f = null;
ref Foo fr = f;
[/code]
Why? First: null isn't an lvalue and even if "Foo f;" is one: if 
it would be allowed, you have a useless reference, because it is 
null and you can't assign a valid object to it (because you can 
assign ref's just once)
Furthermore it solve the problem which I often annotate: not null 
paramters.
void do_something(ref Foo fr) { <- "fr" can't be null, you can 
trust it without any other validations.
I would love that. :)