// a bunch of little examples of ownership in rust
// ggtowell Oct 2023

fn main() {
    main3()
}

fn main1() {
    let aa = "hello".to_string();
    receiver(aa);
    //println!("{aa}");  // Does not compile, the call to receiver gave up ownership of aa 
}

// becomes owner of aa
fn receiver(aa: String) {
    //aa.push_str("gg");
    println!("{aa}");
}



// after each line in main3, what variables are printable (if any) and what is printed??
fn main3() {
    let s1 = 5;
    {
        println!("A s1 {s1}");
        let s1 = g_o();
        println!("B s1 {s1}");
        let s2 = String::from("hello");    
        println!("C s2 {s2} s1 {s1}");
        let s3 = t_a_g(s2); 
        println!("D s3 {s3}  s1 {s1}");
    } 
    println!("E s1 {s1}");

} 

fn g_o() -> String {             
    let some_string = String::from("yours"); 
    some_string        
}

fn t_a_g(a_string: String) -> String { 
    a_string  
}


// one way of handling ownership is to return the things 
// that the function became an owner of
// this is a poor example because i32 is passed by value (passed by copy??)
fn main4() {
    let (a, b) = r2s2(4,5);
}

fn r2s2(aa:i32, bb:i32) -> (i32, i32) {
    return (aa+5, bb+7)
}