Struct RngGuard 

pub struct RngGuard {
    _private: (),
}

RAII guard for R’s RNG state.

Calls GetRNGstate() on creation and PutRNGstate() on drop. This ensures RNG state is properly saved even if the function panics or returns early.

Example

use miniextendr_api::rng::RngGuard;
use miniextendr_api::ffi::unif_rand;

fn generate_uniform() -> f64 {
    let _guard = RngGuard::new();
    unsafe { unif_rand() }
}

Warning: R Longjumps

This guard relies on Rust’s drop semantics. If R triggers a longjmp (via Rf_error etc.), the destructor will NOT run unless the code is wrapped in with_r_unwind_protect. For functions exposed to R, prefer using #[miniextendr(rng)] which handles this correctly.

Safety

Must be used on R’s main thread. The guard assumes it has exclusive access to R’s RNG state while alive.

Fields

_private: ()

Implementations

impl RngGuard

pub fn new() -> Self

Create a new RNG guard, loading the current RNG state.

Calls GetRNGstate() to load R’s .Random.seed into the RNG.

Safety

Must be called from R’s main thread.

Trait Implementations

impl Default for RngGuard

fn default() -> Self

Returns the “default value” for a type.

impl Drop for RngGuard

fn drop(&mut self)

Executes the destructor for this type.