Macro let_ref_thread_stack_value

macro_rules! let_ref_thread_stack_value {
    ($new_variable:ident, $thread_stack:expr) => { ... };
}

Create a local reference to the value at the top of the threadstack. Even though the top value may have been pushed at a much higher layer in the call stack, the reference has a conservative lifetime to guarantee safety – the same lifetime as a local variable created on the stack where the macro is invoked. If you don’t want to have to worry about lifetimes consider using clone_thread_stack_value instead.

Note that this can panic, but only if you did not provide an initial value when you declared your thread stack.

use threadstack::*;

declare_thread_stacks!(
    FOO: String = String::from("hello world");
);

let_ref_thread_stack_value!(my_reference, FOO);
assert!(my_reference == "hello world");

{
    push_thread_stack_value!("hello universe".into(), FOO);
    let_ref_thread_stack_value!(my_other_reference, FOO);
    assert!(my_other_reference == "hello universe");
}

assert!(my_reference == "hello world");
push_thread_stack_value!("hello galaxy".into(), FOO);
assert!(my_reference == "hello world"); // still is reference to old value!
let_ref_thread_stack_value!(my_reference, FOO); // shadows the old reference
assert!(my_reference == "hello galaxy");