dmgolembiowski/type_erased_vec

A type erased `Vec`.

type_erased_vec

This crate provides a single struct TypeErasedVec, which (as its name says) is a type erased Vec.

When you know what its type is, you can get a slice or Vec back using TypeErasedVec::get or TypeErasedVec::get_mut.

Motivation

When communicating with a world outside Rust (GPU for example), it often wants a raw buffer and some kind of type descriptor.

There were two options for expressing this in Rust:

• Vec<u8> + type descriptor.
• Vec<T>.

The first option is not attractive because Vec<u8> cannot be safely used as Vec<T>, hence we lose the ability of modifying the buffer.

The second option makes all types holding that buffer generic over T, which is not feasible when T must be determined at runtime. For example, buffers can be loaded from a 3D model file on disk, where the file contains type information to be passed to the 3D renderer.

Example

use type_erased_vec::TypeErasedVec;

let mut vec = TypeErasedVec::new::<i32>();

{
    let mut vec_mut = unsafe { vec.get_mut() };
    for i in 0..10 {
        vec_mut.push(i);
    }
}

assert_eq!(unsafe { vec.get::<i32>() }, (0..10).collect::<Vec<_>>());