lien

🚧 Under construction 🚧 This crate is somewhat experimental: the recommended API may change (in semver-compatible ways) in future versions.

Scoped lending of borrowed references as Send-able smart pointers. Like thread::scope without the thread!

A lien is "a right to take possession of a debtor's property as security until a debt or duty is discharged." Similarly, a Lien represents a borrow of something from a Scope. Like a static borrow with & or &mut, this forces the Scope to outlive any Liens made from it, but like an Arc, Lien carries no lifetime (it's atomically reference-counted at runtime), is thread-safe, and can be freely cloned.

let mut greeting = String::from("hello ");

{
    let scope = lien::scope!();
    let mut g = scope.lend_mut(&mut greeting);

    thread::spawn(move || {
        g.push_str("beautiful ");
    });
}

greeting.push_str("world");
assert_eq!(greeting, "hello beautiful world");

Smart pointers

• Lien: a bare scope token.
• Ref: a sendable shared reference (like &T).
• RefMut: a sendable exclusive reference (like &mut T).

Both Ref and RefMut support sub-borrowing through Ref::map / RefMut::map, which lets you re-lend fields against the original scope.

#[no_std]

Disable the std feature:

[dependencies]
lien = { version = "0.1", default-features = false }