Struct abi_stable::sabi_types::Constructor

#[repr(transparent)]
pub struct Constructor<T>(pub extern "C" fn() -> T);

Newtype wrapper to pass function pointers to const fn.

A workaround for it not being possible to get a function pointer within a const fn, since it’s possible to pass structs that happen to have function pointer fields.

Every impl of this type delegates the impl to the return value of the wrapped function (which it calls every time),don’t use those impls if the function is likely expensive.

Example

use abi_stable::{
    sabi_types::Constructor,
    std_types::{RNone, ROption, RSome},
};

extern "C" fn returns_100() -> ROption<u32> {
    RSome(100)
}

extern "C" fn returns_100b() -> ROption<u32> {
    RSome(100)
}

extern "C" fn returns_200() -> ROption<u32> {
    RSome(200)
}

extern "C" fn returns_none() -> ROption<u32> {
    RNone
}

const A: Constructor<ROption<u32>> = Constructor(returns_100);
const B: Constructor<ROption<u32>> = Constructor(returns_100b);
const C: Constructor<ROption<u32>> = Constructor(returns_200);
const D: Constructor<ROption<u32>> = Constructor(returns_none);

assert_eq!(A, A);
assert_eq!(B, B);
assert_eq!(C, C);
assert_eq!(D, D);

assert_eq!(A, B);

assert_ne!(A, C);
assert_ne!(A, D);
assert_ne!(B, C);
assert_ne!(C, D);

Tuple Fields

0: extern "C" fn() -> T

Implementations

impl<T> Constructor<T>

pub fn get(self) -> T

Constructs a T by calling the wrapped function.

Trait Implementations

impl<T> Clone for Constructor<T>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for Constructor<T>

where T: Debug,

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

Formats the value using the given formatter.

impl<T> Display for Constructor<T>

where T: Display,

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

Formats the value using the given formatter.

impl<T> GetStaticEquivalent_ for Constructor<T>

where T: __StableAbi,

type StaticEquivalent = _static_Constructor<<T as GetStaticEquivalent_>::StaticEquivalent>

The 'static equivalent of Self

impl<T> Ord for Constructor<T>

where T: Ord,

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl<T> PartialEq for Constructor<T>

where T: PartialEq,

fn eq(&self, other: &Self) -> 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<T> PartialOrd for Constructor<T>

where T: PartialOrd,

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T> StableAbi for Constructor<T>

where T: __StableAbi,

type IsNonZeroType = True

Whether this type has a single invalid bit-pattern.

const LAYOUT: &'static TypeLayout = _

The layout of the type provided by implementors.

const ABI_CONSTS: AbiConsts = _

const-equivalents of the associated types.

impl<T> Copy for Constructor<T>

impl<T> Eq for Constructor<T>

where T: Eq,