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Comment by jdcasale

6 months ago

I am also struggling to see the difference between this and language-level support for an arena allocator with RAII.

6 comments

jdcasale

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lerno  6 months ago

You can certainly do it with RAII. However, what if a language lacks RAII because it prioritizes explicit code execution? Or simply want to retain simple C semantics?

Because that is the context. It is the constraint that C3, C, Odin, Zig etc maintains, where RAII is out of the question.

  • imtringued  6 months ago

    If you want RAII to be explicit, then show an error if you fail to call the destructor. That's it.

    • lerno  6 months ago

      Ok then I understand what you mean (I couldn't respond directly to your answer, maybe there is a limit to nesting in HN?).

      Let me respond in some more detail then to at least answer why C3 doesn't have RAII: it tries to the follow that data is inert. That is – data doesn't have behaviour in itself, but is acted on by functions. (Even though C3 has methods, they are more a namespacing detail allowed to create methods that derive data from the value, or mutate it. They are not intended as organizational units)

      To simplify what the goal is: data should be possible to create or destroy in bulk, without executing code for each individual element. If you create 10000 objects in a single allocation it should be as cheap to free (or create) as a single object.

      We can imagine things built into the type system, but then we will need these unsafe constructs where a type is converted from its "unsafe" creation to its "managed" type.

      I did look at various cheap ways of doing this through the type system, but it stopped resembling C and seemed to put the focus on resource management rather than the problem at hand.

      So that is why it's closer to C than Rust.