# Binds

The `Binds` trait defines how an actor's ports are associated with the message types it can receive remotely.
```rust
pub trait Binds<A: Actor>: RemoteActor {
    fn bind(ports: &Ports<A>);
}
```
Implementing `Binds<A>` allows the system to determine which messages can be routed to an actor instance of type `A`.

## Code Generation

In most cases, you do not implement this trait manually. Instead, the `#[export]` macro generates the appropriate `Binds<A>` implementation by registering the actor's supported message types.

For example:
```rust
#[hyperactor::export(
    spawn = true,
    handlers = [ShoppingList],
)]
struct ShoppingListActor;
```
Expands to:
```rust
impl Binds<ShoppingListActor> for ShoppingListActor {
    fn bind(ports: &Ports<Self>) {
        ports.bind::<ShoppingList>();
    }
}
```
This ensures that the actor is correctly wired to handle messages of type `ShoppingList` when used in a remote messaging context.