auto limitation?

[Namespace]

You mean so?
ref Variant get() {
     return this._num; // with Variant _num;
}

alias get this;

and then:
int i = zahl.get!int?
No. Then I use my solution as you can see on DPaste. If Variant 
works only this way I can also set float to the return type an 
cast if I need to int.
And with my solution I have in calculation a numeric value and 
doesn't have to cast with Variant's get method.