🗂️ resman

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:

• Uses [downcast-rs] instead of [mopa] for downcasting types.
• Adds Debug and PartialEq implementations for borrow types when the resource type implements those traits.
• Returns None instead of panicking for try_borrow* functions when the resource is already borrowed.

Usage

Add the following to Cargo.toml

```toml resman = "0.6.0"

or

resman = { version = "0.6.0", features = ["debug"] } ```

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"

} ```

Features

• "debug":

  The Debug implementation for Resources will use the Debug implementation for the values when printed. This requires that all Resources to also implement Debug.

  Given the following:

  rust let mut resources = Resources::default(); resources.insert(1u32); println!("{:?}", resources);

  Without "debug" feature:

  rust {u32: ".."}

  With "debug" feature:

  rust {u32: 1}

See Also

• [anymap]: Map of any type, without multiple mutable borrows.
• [shred]: Contains Resources type, plus a task dispatcher.

License

Licensed under either of

• Apache License, Version 2.0, ([LICENSE-APACHE] or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license ([LICENSE-MIT] or https://opensource.org/licenses/MIT)

at your option.

Contribution

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.