Ownership semantics

[maik klein via Digitalmars-d-learn]

I recently asked a question about ownership semantics in D 
https://stackoverflow.com/questions/35115702/how-do-i-express-ownership-semantics-in-d

But a few minutes ago I found an answer on SO that could 
potentially explain a lot.

http://stackoverflow.com/a/35114945/944430

Sadly it has some pseudo code in it so I implemented it with 
std.experimental.allocator

struct UniquePtr(T) {
     import std.experimental.allocator;
     private T* ptr = null;

     @disable this(this); // This disables both copy construction 
and opAssign

     this(Args...)(auto ref Args args){
         ptr = theAllocator.make!T(args);
     }

     ~this() {
         theAllocator.dispose(ptr);
     }

     inout(T)* get() inout {
         return ptr;
     }

     // Move operations
     this(UniquePtr!T that) {
         this.ptr = that.ptr;
         that.ptr = null;
     }

     ref UniquePtr!T opAssign(UniquePtr!T that) { // Notice no 
"ref" on "that"
         import std.algorithm.mutation;
         swap(this.ptr, that.ptr); // We change it anyways, 
because it's a temporary
         return this;
     }
}

Is this code correct? One problem that I have is

UniquePtr!int[int] map;

will result in a memory exception and I have no idea why.