Struct abi_stable::sabi_types::Constructor [−][src]
#[repr(transparent)]pub struct Constructor<T>(pub extern "C" fn() -> T);
Expand description
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);
Tuple Fields
0: extern "C" fn() -> T
Implementations
Trait Implementations
type StaticEquivalent = _static_Constructor<__GetStaticEquivalent<T>>
This method returns an ordering between self
and other
values if one exists. Read more
This method tests less than (for self
and other
) and is used by the <
operator. Read more
This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
This method tests greater than (for self
and other
) and is used by the >
operator. Read more
type IsNonZeroType = True
type IsNonZeroType = True
Whether this type has a single invalid bit-pattern. Read more
The layout of the type provided by implementors.
const
-equivalents of the associated types.
Auto Trait Implementations
impl<T> RefUnwindSafe for Constructor<T>
impl<T> Send for Constructor<T>
impl<T> Sync for Constructor<T>
impl<T> Unpin for Constructor<T>
impl<T> UnwindSafe for Constructor<T>
Blanket Implementations
Mutably borrows from an owned value. Read more
type ROwned = T
type ROwned = T
The owned type, stored in RCow::Owned
type ForSelf = WithMetadata_<T, T>
type ForSelf = WithMetadata_<T, T>
This is always WithMetadata_<Self, Self>
Compares the address of self
with the address of other
. Read more
Emulates the pipeline operator, allowing method syntax in more places. Read more
The same as piped
except that the function takes &Self
Useful for functions that take &Self
instead of Self
. Read more
The same as piped
, except that the function takes &mut Self
.
Useful for functions that take &mut Self
instead of Self
. Read more
Mutates self using a closure taking self by mutable reference, passing it along the method chain. Read more
Observes the value of self, passing it along unmodified. Useful in long method chains. Read more
Performs a conversion with Into
.
using the turbofish .into_::<_>()
syntax. Read more
Performs a reference to reference conversion with AsRef
,
using the turbofish .as_ref_::<_>()
syntax. Read more
Performs a mutable reference to mutable reference conversion with AsMut
,
using the turbofish .as_mut_::<_>()
syntax. Read more
unsafe fn transmute_element<T>(
self
) -> <Self as CanTransmuteElement<T>>::TransmutedPtr where
Self: CanTransmuteElement<T>,
unsafe fn transmute_element<T>(
self
) -> <Self as CanTransmuteElement<T>>::TransmutedPtr where
Self: CanTransmuteElement<T>,
Transmutes the element type of this pointer.. Read more
type Type = T
type Type = T
This is always Self
.
Converts a value back to the original type.
Converts a mutable reference back to the original type.
Converts a box back to the original type.
Converts an Arc back to the original type. Read more
Converts an Rc back to the original type. Read more
Converts a value back to the original type.
Converts a reference back to the original type.
Converts a mutable reference back to the original type.
Converts a box back to the original type.
Converts an Arc back to the original type.
Converts an Rc back to the original type.