On Sunday, 11 May 2014 at 08:59:42 UTC, Walter Bright wrote:
D also cannot be performance competitive with C++ if pervasive ARC is used and memory safety is retained. Rust is attempting to solve this problem by using 'borrowed' pointers, but this is unproven technology, see my reply to Manu about it.
I work in a C++ shop and as I see it, resource management is becoming a solved problem:
- resource owners holds a std::unique_ptr<T> on them. Resource release is taken care by C++ destructors normally. That means to be exception-safe, each resource type must better have its class. - resource users eventually "borrow" the resource by taking a raw pointer out of the unique pointer. What Rust would do with lifetimes here is ensure that the resource is still there since move semantics seems pervasive in this language. In C++ we ensure the resource holder outlive the users. - std::shared_ptr is not needed with such constraints. This means no cycles in the object graph. TBH I have yet to find a dependency scheme that can't be done that way.
When I use D I can't help but think that releasing resources feels more manual and error-prone ("oops that resource should have been a struct not a class" and such traps).
I do not have huge concerns about D GC, but I would be glad to have more support for owned pointers (ie. Unique!T in Phobos or better). I have no idea how to make it safe ie. ensure the resource outlive its users.
