Struct Arena 

pub struct Arena {
    data: RefCell<Vec<Pin<Box<dyn Any>>>>,
}

A really dumb arena implementation intended not for efficiency but rather to prolong lifetimes.

Fields

data: RefCell<Vec<Pin<Box<dyn Any>>>>

List of values inserted into the arena. They cannot be moved out from the box or dropped until the arena is dropped.

The use of Box is needed to ensure the address of the value is stable. The Pin and dyn Any parts are just for fun and/or convenience. The pin is expressing the “don’t move” constraint but is neither necessary nor sufficient for soundness (it doesn’t prevent drops), and the dyn Any is just to capture the destructor but we don’t do any downcasting.

Implementations

impl Arena

pub fn new() -> Self

pub fn insert<T>(&self, value: T) -> &T

where T: Any,

Trait Implementations

impl Default for Arena

fn default() -> Self

Returns the “default value” for a type.