Struct Userdata 

pub struct Userdata { /* private fields */ }

A Lua userdata object — a GC-managed handle wrapping a host-side payload (an io file handle, a newproxy identity token, or an embedder-supplied Rust value) plus an optional metatable.

Implementations

impl Userdata

pub fn metatable(&self) -> Option<Gc<Table>>

This userdata’s metatable, if one is attached.

pub fn set_metatable(&mut self, mt: Option<Gc<Table>>)

Install (or clear) this userdata’s metatable.

pub fn file(&self) -> &FileHandle

The file handle behind this userdata (all io userdata are files; the Empty proxy variant is only constructed by newproxy and surfaces via Self::is_proxy, so callers reaching .file() must already know they hold a file handle — luna’s io builtins all guard with is_proxy() or Userdata matching before unpacking).

pub fn file_mut(&mut self) -> &mut FileHandle

Mutable variant of Self::file.

pub fn is_proxy(&self) -> bool

True for newproxy userdata — they have no host payload, only a metatable and identity. io builtins reject these with the PUC “bad argument” error rather than panicking on file().

pub fn is_host(&self) -> bool

True for B8 host userdata (embedder-supplied T: 'static).

pub fn downcast<T: Any + 'static>(&self) -> Option<&T>

Borrow the host payload as &T if this userdata holds a T. Returns None when the userdata isn’t a host payload, or holds a different T. Embedders typically reach this through crate::vm::Vm::userdata_borrow or via a Value::Userdata match arm.

pub fn downcast_mut<T: Any + 'static>(&mut self) -> Option<&mut T>

Mutable borrow variant of Self::downcast.