Crate tany

This crate provides a type-erased values as replacement for Box<dyn Any> that can store small values inline without heap allocation.

TAny is a type-erased value that can store any value of any type that implements Send, Sync and is 'static. LTAny is relaxed version of TAny that doesn’t require Send, Sync bounds.

Usage

use tany::TAny;

// u32 fits inline storage, so no allocation is performed.
let mut a: TAny = TAny::new(42u32);

// Get reference to the value.
let r: &u32 = a.downcast_ref::<u32>().unwrap();

// Get reference to the value.
let r: &mut u32 = a.downcast_mut::<u32>().unwrap();

// Take ownership of the value.
let Ok(a) = a.downcast::<u32>() else {
    panic!();
};


let already_boxed = Box::new([1u32; 10]);


// Construct TAny from already boxed value.
// If type doesn't fit into the storage, the box is used as is,
// otherwise value is unboxed.
let a: TAny = TAny::from_box(already_boxed);

assert_eq!(a.downcast_ref::<[u32; 10]>().unwrap(), &[1u32; 10]);

use core::any::Any;

let any: Box<dyn Any + Send + Sync> = Box::new(42u32);

// Construct TAny from existing Box<dyn Any>.
let a: TAny = TAny::from_any(any); // Or use `From<Box<dyn Any + Send + Sync>>` trait.

assert_eq!(a.downcast_ref::<u32>().unwrap(), &42);

Structs

LTAny

dyn Any with fixed-size inlined storage. Types that fit in the storage are stored without allocation. Types that are too large are boxed. Stored types may not implement Send and Sync. For thread-safe version see TAny.

TAny

dyn Any with fixed-size inlined storage. Types that fit in the storage are stored without allocation. Types that are too large are boxed. Requires Send or Sync. For thread-local version see LTAny.