[−][src]Struct sp_runtime_interface::pass_by::Enum
The implementation of the pass by enum strategy. This strategy uses an u8
internally to pass
the enum between wasm and the host. So, this strategy only supports enums with unit variants.
Use this type as associated type for PassBy
to implement this strategy for a type.
This type expects the type that wants to implement this strategy as generic parameter. Besides
that the type needs to implement TryFrom<u8>
and From<Self> for u8
.
PassByEnum
is a derive macro to implement this strategy.
Example
#[derive(Clone, Copy)] enum Test { Test1, Test2, } impl From<Test> for u8 { fn from(val: Test) -> u8 { match val { Test::Test1 => 0, Test::Test2 => 1, } } } impl std::convert::TryFrom<u8> for Test { type Error = (); fn try_from(val: u8) -> Result<Test, ()> { match val { 0 => Ok(Test::Test1), 1 => Ok(Test::Test2), _ => Err(()), } } } impl PassBy for Test { type PassBy = Enum<Self>; }
Trait Implementations
impl<T: Copy + Into<u8> + TryFrom<u8>> PassByImpl<T> for Enum<T>
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fn into_ffi_value(
instance: T,
_: &mut dyn FunctionContext
) -> Result<Self::FFIType>
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instance: T,
_: &mut dyn FunctionContext
) -> Result<Self::FFIType>
fn from_ffi_value(_: &mut dyn FunctionContext, arg: Self::FFIType) -> Result<T>
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impl<T: Copy + Into<u8> + TryFrom<u8>> RIType for Enum<T>
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The type is passed as u8
.
The value is corresponds to the discriminant of the variant.
Auto Trait Implementations
impl<T> RefUnwindSafe for Enum<T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
impl<T> Send for Enum<T> where
T: Send,
T: Send,
impl<T> Sync for Enum<T> where
T: Sync,
T: Sync,
impl<T> Unpin for Enum<T> where
T: Unpin,
T: Unpin,
impl<T> UnwindSafe for Enum<T> where
T: UnwindSafe,
T: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> MaybeRefUnwindSafe for T where
T: RefUnwindSafe,
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T: RefUnwindSafe,
impl<T> RIType for T where
T: PassBy,
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T: PassBy,
type FFIType = <<T as PassBy>::PassBy as RIType>::FFIType
The ffi type that is used to represent Self
.
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<V, T> VZip<V> for T where
V: MultiLane<T>,
V: MultiLane<T>,