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> you can write entire Rust programs without once calling `free` manually. If you mean "drop," it's just syntactic sugar for calling a trait that manually deal

> you can write entire Rust programs without once calling `free` manually. If you mean "drop," it's just syntactic sugar for calling a trait that manually deallocates the memory and that you're free to reimplement. It feels like people are equating "manual memory management" with "onerous memory management." People are usually going to want to do the boring thing with memory, and everything in the standard library by default does the boring thing with memory. If you write boring structs and enums, you'll derive boring memory management. But it's not part of the language, it's part of the library.

lolinder 2y ago
> If you mean "drop," it's just syntactic sugar for calling a trait that manually deallocates the memory and that you're free to reimplement. I meant `free` because I'm contrasting with C. > It feels like people are equating "manual memory management" with "onerous memory management." Manual memory management is onerous, but I'm very specifically talking about manual. If I can write a whole program without thinking about memory, the language does not require manual memory management. It may support it, but it doesn't require it the way that C or Zig do. You do not "have to explicitly manage memory" as OP claimed.
tialaramex 2y ago
You can't call Drop::drop for type T at all. Try it if you don't believe me. It would be unacceptable to allow this because Drop::drop says it only takes a mutable reference &mut T (and indeed it does) but now the thing is destroyed, so, that wasn't just a mutable reference at all! You can call core::mem::drop<T> but well, look at it, here's the code: pub fn drop<T>(_x: T) {} Like, duh, we give it a T and then it doesn't give anything, the T is gone. That's not magic library code by the way, if we make our own: pub fn vanish<T>(_x: T) {} Now we can call our vanish function and the same happens. So yeah, automatic memory management.
- consteval 2y ago
  To be fair I don't think this is enough to say automatic memory management, otherwise C++ would be automatic memory management too (and maybe it is, just poorly implemented?)
  - tialaramex 2y ago
    Yes, C++ has automatic memory management. As with the rest of the language, the automatic memory mangement requires that your program has no mistakes - which requires inhuman amounts of care during implementation and testing. So, that's obviously a spectacularly bad idea, but it's still automatic memory management.

lolinder 2y ago

> If you mean "drop," it's just syntactic sugar for calling a trait that manually deallocates the memory and that you're free to reimplement. I meant `free` because I'm contrasting with C. > It feels like people are equating "manual memory management" with "onerous memory management." Manual memory management is onerous, but I'm very specifically talking about manual. If I can write a whole program without thinking about memory, the language does not require manual memory management. It may support it, but it doesn't require it the way that C or Zig do. You do not "have to explicitly manage memory" as OP claimed.

tialaramex 2y ago

You can't call Drop::drop for type T at all. Try it if you don't believe me. It would be unacceptable to allow this because Drop::drop says it only takes a mutable reference &mut T (and indeed it does) but now the thing is destroyed, so, that wasn't just a mutable reference at all! You can call core::mem::drop<T> but well, look at it, here's the code: pub fn drop<T>(_x: T) {} Like, duh, we give it a T and then it doesn't give anything, the T is gone. That's not magic library code by the way, if we make our own: pub fn vanish<T>(_x: T) {} Now we can call our vanish function and the same happens. So yeah, automatic memory management.

consteval 2y ago
To be fair I don't think this is enough to say automatic memory management, otherwise C++ would be automatic memory management too (and maybe it is, just poorly implemented?)
- tialaramex 2y ago
  Yes, C++ has automatic memory management. As with the rest of the language, the automatic memory mangement requires that your program has no mistakes - which requires inhuman amounts of care during implementation and testing. So, that's obviously a spectacularly bad idea, but it's still automatic memory management.