import std.stdio;
import std.conv : to;

class Ref(T) {
private:
	T _obj;

public:
	this(T obj) {
		assert(obj !is null);
		
		this._obj = obj;
	}
	
	invariant() {
		assert(obj !is null);
	}
	
	@property
	inout(T) GetObj() inout {
		return this._obj;
	}
	
	alias GetObj this;
}

mixin template TRef(Type) {
private:
	Ref!(Type) _reference;

	void InitRef() {
		this._reference = new Ref!(Type)(this);
	}

public:
	@property
	inout(Ref!(Type)) GetRef() inout {
		return this._reference;
	}
}

class Foo {
private:
	string _msg;

public:
	mixin TRef!(Foo);
	
	alias GetRef this;
	
	this(string msg) {
		InitRef();
		
		this.Set(msg);
	}
	
	void Set(string msg) {
		this._msg = msg;
	}
	
	void echo() const {
		writeln(this._msg);
	}
}

void foo(Foo f) {
	f.echo();
}

void bar(Ref!(Foo) rf) {
	rf.echo();
	writeln("----");
	Foo f = rf;
	f.echo();
}

void main() {
	Foo f = new Foo("foobar");
	
	foo(f);
	bar(f);
}