Method new

aiscript-arena/src/arena.rs:132–149

Create a new arena with the given garbage collector tuning parameters. You must provide a closure that accepts a `&Mutation<'gc>` and returns the appropriate root.

(f: F)

    /// Create a new arena with the given garbage collector tuning parameters. You must provide a
    /// closure that accepts a `&Mutation<'gc>` and returns the appropriate root.
    pub fn new<F>(f: F) -> Arena<R>
    where
        F: for<'gc> FnOnce(&'gc Mutation<'gc>) -> Root<'gc, R>,
    {
        unsafe {
            let context = Box::new(Context::new());
            // Note - we cast the `&Mutation` to a `'static` lifetime here,
            // instead of transmuting the root type returned by `f`. Transmuting the root
            // type is allowed in nightly versions of rust
            // (see https://github.com/rust-lang/rust/pull/101520#issuecomment-1252016235)
            // but is not yet stable. Casting the `&Mutation` is completely invisible
            // to the callback `f` (since it needs to handle an arbitrary lifetime),
            // and lets us stay compatible with older versions of Rust
            let mc: &'static Mutation<'_> = &*(context.mutation_context() as *const _);
            let root: Root<'static, R> = f(mc);
            Arena { context, root }
        }
    }

    /// Similar to `new`, but allows for constructor that can fail.
    pub fn try_new<F, E>(f: F) -> Result<Arena<R>, E>