Runtime managed resource borrowing.
This library provides a map that can store one of any type, as well as mutable borrows to each type at the same time.
Note: This implementation is extracted from [shred], with the following differences:
downcast-rs] instead of [mopa] for downcasting types.Debug and PartialEq implementations for borrow types when the resource type implements those traits.None instead of panicking for try_borrow* functions when the resource is already borrowed.Add the following to Cargo.toml
toml
resman = "0.1.0"
In code:
```rust use resman::Resources;
struct A(u32); struct B(u32);
fn main() { let mut resources = Resources::default();
resources.insert(A(1));
resources.insert(B(2));
// We can validly have two mutable borrows from the `Resources` map!
let mut a = resources.borrow_mut::<A>();
let mut b = resources.borrow_mut::<B>();
a.0 = 2;
b.0 = 3;
// We need to explicitly drop the A and B borrows, because they are runtime
// managed borrows, and rustc doesn't know to drop them before the immutable
// borrows after this.
drop(a);
drop(b);
// Multiple immutable borrows to the same resource are valid.
let a_0 = resources.borrow::<A>();
let _a_1 = resources.borrow::<A>();
let b = resources.borrow::<B>();
println!("A: {}", a_0.0);
println!("B: {}", b.0);
// Trying to mutably borrow a resource that is already borrowed (immutably
// or mutably) returns `None`.
let a_try_borrow_mut = resources.try_borrow_mut::<A>();
let exists = if a_try_borrow_mut.is_some() {
"Some(..)"
} else {
"None"
};
println!("a_try_borrow_mut: {}", exists); // prints "None"
} ```
anymap]: Map of any type, without multiple mutable borrows.shred]: Contains Resources type, plus a task dispatcher.Licensed under either of
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.