as_any_min/
lib.rs

1//! This is a very minimal crate that makes it easier to work
2//! with traits that implement `Any` by allowing you to easily 
3//! upcast to it.
4//! 
5//! # Example
6//! 
7//! ```
8//! use core::any::Any;
9//! use as_any_min::AsAny;
10//! 
11//! struct MyStruct;
12//! trait MyTrait {}
13//! impl MyTrait for MyStruct {}
14//! 
15//! /* Note that AsAny is automatically implemented for all 
16//!     structs that implement Any, so there is no need to 
17//!     implement it manually (in fact it won't compile if
18//!     you try to) */
19//! 
20//! fn main() {
21//!     // my_variable is now a trait object, which is the
22//!     //  main use case for the AsAny trait.
23//!     let my_variable: &dyn MyTrait = &MyStruct;
24//! 
25//!     let my_any_variable: &dyn Any = my_variable.as_any();
26//! }
27//! ```
28//! 
29//! # Without Using `AsAny`
30//! 
31//! Since rust doesn't (currently) have any built in way to
32//! upcast from a trait object to another trait (such as `Any`), 
33//! this won't compile.
34//! 
35//! ```compile_fail
36//! use core::any::Any;
37//! 
38//! struct MyStruct;
39//! trait MyTrait {}
40//! impl MyTrait for MyStruct {}
41//! 
42//! fn main() {
43//!     let my_variable: &dyn MyTrait = &MyStruct;
44//! 
45//!     let my_any_variable: &dyn Any = my_variable;
46//! }
47//! ```
48
49#![no_std]
50#![warn(missing_docs)]
51
52use core::any::Any;
53
54/// This trait allows anything that implements `Any` to be easily 
55/// upcast to `Any`.
56/// 
57/// It is automatically implemented for all structs that implement
58/// `Any`. This is useful because there isn't an automatic way to 
59/// upcast a trait object.
60pub trait AsAny {
61    /// This returns the struct as a `&dyn Any`
62    fn as_any(&self) -> &dyn Any;
63
64    /// This returns the struct as a `&dyn mut Any`
65    fn as_any_mut(&mut self) -> &mut dyn Any;
66}
67
68impl<T> AsAny for T
69    where T: Any
70{
71    fn as_any(&self) -> &dyn Any {
72        self
73    }
74    fn as_any_mut(&mut self) -> &mut dyn Any {
75        self
76    }
77}
as_any_min/lib.rs

as_any_min/
lib.rs
