On Saturday, May 26, 2012 04:04:51 Mehrdad wrote: > Would you mind explaining the difference between clear(), delete, > and __dtor/etc? I think it's a little confusing for me.
clear destroys the object (by calling its finalizer or destructor) and then in the case of classes, it zeroes out its vtable so that if you accidentally the object after clearing it, it'll blow up rather than getting weird, non- deterministic behavior. In the case of structs, I think that it puts the object in its init state, but I'm not sure. clear does _not_ free the object's memory. It merely destroys the object so that whatever other resources it references can be released (or just unreferenced in the case of GC heap allocated objects that it references). delete does what it does in C++. It destroys the object and then frees the memory. It was decided that having a language construct which freed memory on the GC heap was too dangerous and error-prone and shouldn't be encouraged, so it's being removed. It's still quite possible however, to create a function which destroys and object and then tells the GC to free that object's memory using the stuff in core.memory. __dtor is simply the object's destructor. Calling it calls that function. However, I don't believe that it destroys what the object references (since that would require doing more than simply calling the destructor). As I recall, you have to do something else which is a bit involved to do that. There was a discussion on it recently, but I don't recall the details unfortunately. In the long run, I expect that anyone who really wants to use something akin to delete will likely use custom allocators (e.g. using malloc and free) rather than using the GC heap, possibly with some sort of ref-counting. So, you'd get something like //non-ref-counted auto a = ca.allocate!MyClass(args); ca.deallocate(a); or //ref-counted { auto a = ca.allocate!MyClass(args); } //a has left scope, so its ref-count reach zero, and it was destroyed Obviously we don't have the custom allocator stuff fully ironed out yet though. Andrei has been working on those, but he's been a bit swamped, so who knows when we'll see them. - Jonathan M Davis