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> This seems like an extremely low bar. Is it, though? Most mainstream languages fail to support anything resembling RAII, at least as first-class support. Do

• asyx 1y ago
  Rust simply because the constructor being a static method on the type that can return basically anything including optional and result types and copy / move semantics are handled very easily through macros instead of constructor / assignment operator overrides.
  • deleted 1y ago
    [deleted]
  • motorest 1y ago
    > Rust simply because the constructor being a static method (...) This assertion makes no sense. RAII is not defined by whether you use factory functions or special member functions to initialize an object. In fact, RAII is only incidentally related ro memory management. RAII is a strategy to manage any and all types of resources, ranging from memory management to even files and TCP connections, by leveraging assurances that the runtime provides regarding scopes and object life cycles. None of this changes if you employ factory functions to initialize resources.
• palata 1y ago
  Not that I agree with the condescending parent (e.g. "you're still stuck with a C++ programmer you need to figure out how to socialize with"), but... > Most mainstream languages fail to support anything resembling RAII Wikipedia says: "RAII is associated most prominently with C++, where it originated, but also Ada,[3] Vala,[4] and Rust" > Do you actually have an example of a language that does a better job at resource management than C++? They don't necessarily offer a pattern like RAII, but what about "try-with-resources" in Java, or "use" in Kotlin that goes with `AutoCloseable`? And what about "using" in C#? What about "defer" in Swift? I find those simpler than RAII.
  • pjmlp 1y ago
    One caveat though, you need to pair those with static analysis tooling, if you want to ensure developers don't forget to make use of them.
    • palata 1y ago
      How does RAII solve that? Developers can "forget" to use RAII, right? Or are you saying that it's easier to spot because RAII requires quite a bunch of boilerplate (whereas a one-liner like "defer" is easier to forget)? Not criticising, really trying to understand :-).
      • pjmlp 1y ago
        RAII when supported natively by the language, is done at the implementation level, not the usage point. So in languages like Rust, D, Ada, Swift, C++, the compiler will do the rest unless you go out of your way to avoid the call to take place, like placing a value type on the heap using plain pointers. With the other approach, even if you implement IDisposable, AutoCloseable, ContextManager and similar, you have to remember to manually write the code pattern that takes care of calling close(), or whatever the method/function happens to be called. In languages with good support for FP patterns, like trailing lambdas, currying and such, there is another pattern, that is much safer, in case you don't want a static analysis tool to track resource usage, the with pattern. You do something like withDBConnection connection (fun db -> all related db operations). Assuming the lambda doesn't do naughty things to have db parameter escape the scope, the withDBConnection function will take care of handling the whole connection lifecycle.
    • znkr 1y ago
      I agree, this is a real benefit of RAII compared to defer. That said, there are disadvantages of making the resource freeing part invisible. Not having to debug destructors that do network IO (e.g. closing a buffered writer that writes to the other side of the world) or expensive computation (e.g. buffered IO writing to a compressor) is a define plus. Don’t get me started on error handling…
• tialaramex 1y ago
  Obviously a language with linear types is just better at this, such as Austral. In terms of languages you'd actually deploy today Rust is better both at this narrow feature and more broadly.
• znkr 1y ago
  When I switched from C++ to a bunch of other languages, I missed RAII initially. However, I quickly learned that other languages just do it differently and often even better (ever had to check an error when closing a resource?). Nowadays, I think that RAII is a solution to a C++ problem and other languages have a better solution for resource management (try-with-resources in Java, defer in Go, with in Python).
  • motorest 1y ago
    > However, I quickly learned that other languages just do it differently and often even better (ever had to check an error when closing a resource?). I don't think that's even conceptually the same. The point of RAII is that resource deallocation is ensured, deterministic, and built into the happy path. Once you start to throw errors and relying on those to manage resources, you're actually dealing the consequences of not having RAII.
  • oytis 1y ago
    > try-with-resources in Java, defer in Go, with in Python Or 'goto error8;' in C. Still RAII is much more convenient, especially for cases where you allocate a lot of interdependent resources at different time points. It keeps deallocation logic close to allocation logic (unlike, say, defer), makes sure deallocation always happens in the reverse order of allocations and doesn't force you to create a nested scope each time you allocate a resource
• pjmlp 1y ago
  Ada/SPARK, with better ergonomics than Rust, but its use will stay niche in high integrity computing.