By default, all fields within a struct are private to the module it is created in. This has its uses; for example, if you want to protect a value within the struct, you can make it only accessible via a read/write function, as shown in the following example:
// readwrite.rs
pub struct RWData
{
pub X: i32,
Y: i32
}
static mut rwdata: RWData = RWData {X: 0, Y: 0};
pub fn store_y(val: i32)
{
unsafe { rwdata.Y = val; }
}
pub fn new_y() -> i32
{
unsafe { rwdata.Y * 6 }
}
// main.rs
mod readwrite;
use readwrite::*;
fn main() {
store_y(6);
println!("Y is now {}", new_y());
}
The code for this section is in the 07/readwrite folder, present in the supporting code bundle provided for this book.
When we build and run this, we will get the following output:
