Troubles creating templated inout objects

[Timoses]

How do I create an inout object with template parameters?

Take following code:

	import std.stdio;
	import std.traits;

	struct S
	{
		int[] arr;
	}

	interface I
	{
		inout(I) opIndex(size_t idx) inout;
	}

	class Test(T) : I
	{
                 // Error: variable 
`onlineapp.Test!(inout(int)[]).Test.member` only parameters or 
stack based variables can be inout
		T member;

		this(inout T mem) inout
		{
			this.member = mem;
		}

		inout(Test!T) get() inout
		{
			return new inout Test!(Unqual!(typeof(member)))(member);
		}

		inout(I) opIndex(size_t idx) inout
		{
			switch (idx)
			static foreach (index, t; T.tupleof)
			{
				case index:
                                         // Error: template 
instance `onlineapp.Test!(inout(int)[])` error instantiating
					return new inout
						Test!(Unqual!(typeof(this.member.tupleof[index])))
									(this.member.tupleof[index]);
                 default:
                 	return null;
			}
		}
	}


	unittest
	{
		auto s = S([1,2,3]);
		auto t = new const Test!S(s);
	}


`Unqual` in this case just turns `inout(int[])` into 
`inout(int)[]`, which is why it complains. That's a side effect 
of this example, however the main question is how one would go 
about achieving something like this idiomatically?

I would like to return a new object and that object should have 
the same mutability as the one creating it.