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::{ROption,RNone,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);

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>

pub fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Copy for Constructor<T>

impl<T> Debug for Constructor<T> where
    T: Debug, 

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

Formats the value using the given formatter.

impl<T> Display for Constructor<T> where
    T: Display, 

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

Formats the value using the given formatter.

impl<T> Eq for Constructor<T> where
    T: Eq, 

impl<T> GetStaticEquivalent_ for Constructor<T> where
    T: __StableAbi, 

type StaticEquivalent = _static_Constructor<__GetStaticEquivalent<T>>

impl<T> Ord for Constructor<T> where
    T: Ord, 

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

This method returns an Ordering between self and other.

#[must_use]pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl<T> PartialEq<Constructor<T>> for Constructor<T> where
    T: PartialEq, 

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

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<T> PartialOrd<Constructor<T>> for Constructor<T> where
    T: PartialOrd, 

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

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

#[must_use]pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]pub fn le(&self, other: &Rhs) -> bool

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

#[must_use]pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]pub fn ge(&self, other: &Rhs) -> bool

This method 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.

pub const LAYOUT: &'static TypeLayout

The layout of the type provided by implementors.

pub const ABI_CONSTS: AbiConsts

const-equivalents of the associated types.