Am 15.11.2012 12:48, schrieb Jonathan M Davis:
Yeah. If the reference passed across were shared, then the runtime should see it as having multiple references, and if it's _not_ shared, that means that you cast shared away (unsafe, since it's a cast) and passed it across threads without making sure that it was the only reference on the original thread. In that case, you shot yourself in the foot by using an @system construct (casting) and not getting it right. I don't see why the runtime would have to worry about that. Unless the problem is that the object is a value type, so when it goes away on the first thread, it _has_ to be destroyed? If that's the case, then it's a pointer that was passed across rather than a reference, and then you've effectively done the same thing as returning a pointer to a local variable, which is @system and again only happens if you're getting @system wrong, which the compiler generally doesn't protect you from beyond giving you an error in the few cases where it can determine for certain that what you're doing is wrong (which is a fairly limited portion of the time). So, as far as I can see - unless I'm just totally missing something here - either you're dealing with shared objects on the heap here, in which case, the object shouldn't be destroyed on the first thread unless you do it manually (in which case, you're doing something stupid in @system code), or you're dealing with passing pointers to shared value types across threads, which is essentially the equivalent of escaping a pointer to a local variable (in which case, you're doing something stupid in @system code). In either case, it's you're doing something stupid in @system code, and I don't see why the runtime would have to worry about it. You shot yourself in the foot by incorrectly using @system code. If you want protection agains that, then don't use @system code. - Jonathan M Davis
Thank you, thats exatcly how I'm thinking too. And because of this it makes absolutley no sense to me to disallow the destruction of a shared struct, if it is allocated on the stack or as a global. If it is allocated on the heap you can't destory it manually anyway because delete is deprecated.
And for exatcly this reason I wanted a code example from Walter. Because just listing a few bullet points does not make a real world use case.
Kind Regards Benjamin Thaut
