class destruction

[ponce via Digitalmars-d-learn]

On Wednesday, 9 September 2015 at 07:19:58 UTC, Q wrote:
> 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)?

Then you have to make sure the class destruction happens and not 
rely on the GC.


> Can I be sure that the Handle is destroyed as soon as the class 
> is destroyed?

I think that yes, struct members are destroyed. But you need to 
make sure the class is destroyed.




> 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.

I'm using the manual method after much hair-pulling: 
http://p0nce.github.io/d-idioms/#GC-proof-resource-class

It absolutely is worse than the C++ situation, however with the 
above pattern leaks will be reported by the GC, which is a nice 
consolation prize.


Alternatively, stick your class in Unique! / Refcounted! / scoped!