On Tue, Mar 12, 2013 at 01:07:07PM -0400, Jack Lloyd wrote:
> If two or more struct initializers have side effects, is the order
> that they run defined?
I'm pretty sure it is, because it's actually part of the type system.
See src/test/run-pass/struct-order-of-eval-2.rs:
struct S { f0: ~str, f1: ~str }
pub fn main() {
let s = ~"Hello, world!";
let _s = S { f1: str::from_slice(s), f0: s };
}
That compiles, but swap the order of the field initializers and:
struct-order-of-eval-2.rs:15:44: 15:45 error: use of moved value: `s`
struct-order-of-eval-2.rs:15 let _s = S { f0: s, f1: str::from_slice(s) };
^
struct-order-of-eval-2.rs:15:21: 15:22 note: `s` moved here because it has
type ~str, which is moved by default (use `copy` to override)
struct-order-of-eval-2.rs:15 let _s = S { f0: s, f1: str::from_slice(s) };
^
So it's important that the first program not be turned into the second
program after the type checking is done.
--Jed
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