Template parameter defaults

[Johann MacDonagh]

I'm wondering if there's a cleaner way to do this:

class Test(T = uint)
{
    this(string s)
    {
    }
}
void main(string[] argv)
{
    auto a = new Test!()("test");
}

I'd *like* to be able to do this:

auto a = new Test("test");

and:

auto a = new Test!double("test");

The only possibility I see is to do this:

alias Test!() Test2;

But that introduces two types a user has to decide between. Any ideas? 
Am I out of luck here?

Thanks