Struct NullOnErr 

pub struct NullOnErr;

Marker type for Result<T, ()> that converts Err(()) to NULL.

This type is used internally by the #[miniextendr] macro when handling Result<T, ()> return types. When the error type is (), there’s no error message to report, so we return NULL instead of raising an error.

Usage

You typically don’t use this directly. When you write:

#[miniextendr]
fn maybe_value(x: i32) -> Result<i32, ()> {
    if x > 0 { Ok(x) } else { Err(()) }
}

The macro generates code that converts Err(()) to Err(NullOnErr) and returns NULL in R.

Note

NullOnErr intentionally does NOT implement Display to avoid conflicting with the generic IntoR for Result<T, E: Display> impl. It has its own specialized IntoR impl that returns NULL on error.

Trait Implementations

impl Clone for NullOnErr

fn clone(&self) -> NullOnErr

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for NullOnErr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for NullOnErr

#[doc(hidden)]

fn assert_fields_are_eq(&self)

🔬This is a nightly-only experimental API. (derive_eq_internals)

#[doc(hidden)]

fn assert_receiver_is_total_eq(&self)

👎Deprecated since 1.95.0:

implementation detail of #[derive(Eq)]

impl PartialEq for NullOnErr

fn eq(&self, other: &NullOnErr) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for NullOnErr

impl StructuralPartialEq for NullOnErr

impl TrivialClone for NullOnErr

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

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