Fighting with alias this: bugs or features?

[trx1]

osa Wrote:

> On 10/26/2010 05:09 PM, Andrei Alexandrescu wrote:
> > Thanks. Defining opAssign for Bar will allow you to use the syntax bar =
> > null and have it nullify the reference.
> 
> I feel stupid, but I do not see how to nullify the Bar reference inside 
> of opAssign. Again, my problem is that I have
> 	Bar x = new Bar( ... );
> and I want x to become null. Is there a workaround for 'cannot 
> implicitly convert expression (null) of type void* to Foo' which does 
> not involve low-level trickery like *cast(void**)&x = null?

A workaround is maybe

struct Foo {}
class Bar {
     Foo foo_;
     alias foo_ this;
}

void main() {
     auto a = new Bar;
     auto b = a;
     a = a.init; //compiles as oppose to a = null;
     writeln(a); // prints null

}

just playing around with the code, so have no explaination for the behaviour