std::boxed

pub struct Box<T, A=Global>(/*private fields*/)
where
  A: Allocator,
  T: ?Sized;

A pointer type uniquely owns a heap allocation of type T. It provides the simplest form of heap allocation in Rust. Boxes also ensure that they never allocate more than isize::MAX bytes.

Box vs Rc

Box provides exclusive ownership of the data on the heap. Exclusive ownership means that a single variable has complete control over a piece of data at any given time.

Allocator

A is an optional generic parameter representing the allocator used to manage the memory. It defaults to Global which is the default global allocator provided by Rust. Allocator is the trait bound on the A parameter.