4 ms·

> When does your constructor & destructor fire when a dynamic array grows? What constructor? And why would a Drop implementation be invoked to move something?

> When does your constructor & destructor fire when a dynamic array grows? What constructor? And why would a Drop implementation be invoked to move something? You've moved it, there's nothing left to drop. > Did you use the copy-and-swap idiom properly? I don't believe I'm familiar with this idiom? From some quick googling this seems to be related to panic safety and ensuring that you don't leave things in an invalid state if a panic happens. It doesn't seem to be RAII-specific, and would also apply to a defer mechanism. > Did you define all the "rule of five" methods? Rule of five? You mean that your Clone implementation must properly handle resources in accordance with your Drop implementation, right? I'm not sure where the other three come in?

QuadrupleA 2y ago
I'm speaking about C++, where blind faith in RAII is widespread, so I don't know if Rust's implementation alleviates some of the accidental complexity. But I suspect any system with constructors / destructors leads to a lot of the same implicit behaviors, unintended complications, and leaky abstractions, and I generally favor explicit Initialize() and Cleanup() functions that you call manually, even in languages that support the implicit/magic stuff.
- estebank 2y ago
  Rust doesn't have constructors*. * Well, it kind of does, in so far there is a Ctor enum variant in the compiler implementation to represent the name of a type in the value namespace, but it is not overridable by end users and has no logic.
- Measter 2y ago
  You were conflating details of C++'s object model and implementation of move semantics with RAII. Rust also makes heavy use of RAII, and the details of its object model and move semantics are not the same as C++'s. The only thing that RAII requires is the concept of ownership, and a cleanup function that the compiler knows about. The one implicit thing here is the automatic insertion of calls to the cleanup function.

QuadrupleA 2y ago

I'm speaking about C++, where blind faith in RAII is widespread, so I don't know if Rust's implementation alleviates some of the accidental complexity. But I suspect any system with constructors / destructors leads to a lot of the same implicit behaviors, unintended complications, and leaky abstractions, and I generally favor explicit Initialize() and Cleanup() functions that you call manually, even in languages that support the implicit/magic stuff.

estebank 2y ago
Rust doesn't have constructors*. * Well, it kind of does, in so far there is a Ctor enum variant in the compiler implementation to represent the name of a type in the value namespace, but it is not overridable by end users and has no logic.
Measter 2y ago
You were conflating details of C++'s object model and implementation of move semantics with RAII. Rust also makes heavy use of RAII, and the details of its object model and move semantics are not the same as C++'s. The only thing that RAII requires is the concept of ownership, and a cleanup function that the compiler knows about. The one implicit thing here is the automatic insertion of calls to the cleanup function.