Function expose_during 

pub fn expose_during<F, R>(f: F) -> R
where
    F: FnOnce() -> R,

Run f with SensitiveString’s Serialize impl exposing inner values.

Use this around code paths that need to serialise-and-deserialise a config struct without destroying its secrets – typically the figment::Figment::from(Serialized::defaults(&config)) + .extract() round-trip in a consumer’s config loader.

Scope and reentrancy

The flag is thread-local. Calls from inside the closure on the same thread observe exposure; calls from other threads do not. Nested calls compose correctly (inner guards restore the outer state on drop). Async callers should be aware that the flag does NOT cross .await boundaries to other threads – keep the round-trip on one thread, or wrap each thread’s section in its own expose_during.

Panic safety

If f panics, the previous flag value is restored via an RAII drop guard before the panic unwinds further.

Examples

use hyperi_rustlib::{SensitiveString, expose_during};
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct Cfg {
    password: SensitiveString,
}

let cfg = Cfg { password: SensitiveString::new("hunter2") };

// Default: serialise redacts.
let json = serde_json::to_string(&cfg).unwrap();
assert!(json.contains("***REDACTED***"));

// Inside expose_during: serialise reveals so a round-trip preserves the value.
let round_tripped: Cfg = expose_during(|| {
    let v = serde_json::to_value(&cfg).unwrap();
    serde_json::from_value(v).unwrap()
});
assert_eq!(round_tripped.password.expose(), "hunter2");

// After the call, default redaction resumes.
let json = serde_json::to_string(&cfg).unwrap();
assert!(json.contains("***REDACTED***"));