Struct rlua::prelude::LuaRegistryKey
source · [−]pub struct LuaRegistryKey { /* private fields */ }
Expand description
An auto generated key into the Lua registry.
This is a handle to a value stored inside the Lua registry. Unlike the Table
or Function
handle types, this handle is Send + Sync + 'static
and can be returned outside of a call to
Lua::context
. Also, rather than calling methods directly on it, you must instead retrieve the
value first by calling Context::registry_value
inside a call to Lua::context
.
It is not automatically garbage collected on Drop, but it can be removed with
Context::remove_registry_value
, and instances not manually removed can be garbage collected
with Context::expire_registry_values
.
Be warned, If you place this into Lua via a UserData
type or a rust callback and rely on
Context::expire_registry_values
, it is very easy to accidentally cause reference cycles
that cannot be automatically collected. The Lua garbage collector is not aware of the registry
handle pattern, so holding onto a RegistryKey
inside Lua may lead to it never being dropped,
and it if it is not droped, Context::expire_registry_values
will never remove the value from
the registry, leading to an uncollectable cycle. Instead of placing a RegistryKey
into Lua
and relying on it being automatically dropped, prefer APIs which the Lua garbage collector
understands, such as UserData::set_i_user_value
/ UserData::get_i_user_value
for UserData
types and Function::bind
for callbacks.