Struct Registry 

pub struct Registry { /* private fields */ }

Chain combinator for Resolver. Registration order = priority order. First match wins.

install() inserts a hook at the front (index 1) of Lua’s package.searchers table, routing all require calls through the registered Resolver chain. Takes priority over Lua’s standard package.preload.

Caching is delegated to Lua’s standard package.loaded. Resolvers do not need to manage their own cache. On the second and subsequent require for the same module, the Resolver is not called.

Lua searcher protocol

The hook conforms to the Lua 5.4 searcher protocol:

• If the searcher returns a function, require calls it as a loader
• If the searcher returns a string, it is collected as a “not found” reason in the error message

The loader receives (name, loader_data) (per Lua 5.4 spec).

Thread safety

Registry itself is Send + Sync (all Resolvers must be Send + Sync). After install(), the Registry is wrapped in Arc and shared via a Lua closure.

Thread safety of the installed hook depends on the mlua feature configuration:

mlua feature	Lua bounds	Implication
(default)	!Send	Lua is confined to one thread. The hook is never called concurrently.
send	Send + Sync	Lua can be shared across threads. Resolver: Send + Sync ensures safe concurrent access.

The Send + Sync bound on Resolver is required for forward compatibility with mlua’s send feature. Without the send feature, Lua is !Send and the hook is inherently single-threaded.

Implementations

impl Registry

pub fn new() -> Self

pub fn add(&mut self, resolver: impl Resolver + 'static) -> &mut Self

Add a Resolver. Registration order = priority order.

pub fn install(self, lua: &Lua) -> Result<()>

Insert a hook at the front of package.searchers.

Consumes self and shares it via Arc. The Registry becomes immutable after install (Resolver priority is finalized).

Returns an error if called more than once on the same Lua instance. Multiple Registries coexisting in the same searchers table would make priority order unpredictable, so this is intentionally prohibited.

Trait Implementations

impl Default for Registry

fn default() -> Self

Returns the “default value” for a type.