User defined type and foreach

[Tony via Digitalmars-d-learn]

I made a stack data type and created an opIndex() so it could be 
turned into a dynamic array, and created empty() (unfortunate 
name), front() and popFront() methods, which I read allow it to 
be used with foreach.

However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use the 
three methods, rather than create a dynamic array.