class destruction

[Q via Digitalmars-d-learn]

Hi. I'm playing around with D for a while and I would like to 
switch. But here is one thing, I need an answer for. In the Docs 
is mentioned that it is not sure that the DTor of a class is 
called. But what if I have struct, which holds a C Handle which 
is destroyed as soon as the struct gets destroyed (more or less 
like a unique pointer) and I stick this struct into a class 
(because I strongly need polymorphism)? Can I be sure that the 
Handle is destroyed as soon as the class is destroyed? Or will 
the handle leak?
If so there are only two ways that come to mind:
1.  the class holds only a pointer to the struct, which is unsafe 
since I must guarantee that the struct lives as long as the class
2. the class gets a close/finalize/destroy method (or is called 
with the built in destroy method), which is a absolute nogo, 
because it is absolutly sure that this can be forgotten. Besides, 
we live in 2015 and that is not C where I have to clean my code 
manually, so this option would be ridiculous :D

I'm gratefull for any answers and ideas.