Marker Traits

Send, Sync, Sized, Unpin และ marker traits อื่นๆ

Send Trait

use std::thread;
use std::sync::Arc;
use std::rc::Rc;

fn main() {
    // Send - safe to transfer between threads

    // Most types are Send
    let data = vec![1, 2, 3];
    thread::spawn(move || {
        println!("Vec in thread: {:?}", data);
    }).join().unwrap();

    // Arc is Send (when T: Send + Sync)
    let arc = Arc::new(42);
    let arc_clone = Arc::clone(&arc);
    thread::spawn(move || {
        println!("Arc in thread: {}", arc_clone);
    }).join().unwrap();

    // Rc is NOT Send
    let rc = Rc::new(42);
    // thread::spawn(move || { println!("{}", rc); });  // Error!
    println!("Rc stays in main: {}", rc);

    println!("\n=== Send Types ===");
    println!("- Primitive types (i32, bool, etc.)");
    println!("- String, Vec<T> where T: Send");
    println!("- Arc<T> where T: Send + Sync");
    println!("- Mutex<T> where T: Send");

    println!("\n=== NOT Send ===");
    println!("- Rc<T> (non-atomic refcount)");
    println!("- Raw pointers (*const T, *mut T)");
}