Accessing a field of a containing class from within a nested class

[Gary Willoughby via Digitalmars-d-learn]

On Wednesday, 1 April 2015 at 18:26:49 UTC, Charles Hixson wrote:
> Perhaps BTree needs to be a class?  I made it a struct because 
> I want it to definitely close properly when it
> goes out of scope.

Maybe `scoped` can help:
http://dlang.org/phobos/std_typecons.html#.scoped