#[non_exhaustive]pub enum KeyState {
CreateComplete,
CreateInProgress,
DeleteComplete,
DeletePending,
Unknown(UnknownVariantValue),
}Expand description
When writing a match expression against KeyState, it is important to ensure
your code is forward-compatible. That is, if a match arm handles a case for a
feature that is supported by the service but has not been represented as an enum
variant in a current version of SDK, your code should continue to work when you
upgrade SDK to a future version in which the enum does include a variant for that
feature.
Here is an example of how you can make a match expression forward-compatible:
# let keystate = unimplemented!();
match keystate {
KeyState::CreateComplete => { /* ... */ },
KeyState::CreateInProgress => { /* ... */ },
KeyState::DeleteComplete => { /* ... */ },
KeyState::DeletePending => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when keystate represents
NewFeature, the execution path will lead to the second last match arm,
even though the enum does not contain a variant KeyState::NewFeature
in the current version of SDK. The reason is that the variable other,
created by the @ operator, is bound to
KeyState::Unknown(UnknownVariantValue("NewFeature".to_owned()))
and calling as_str on it yields "NewFeature".
This match expression is forward-compatible when executed with a newer
version of SDK where the variant KeyState::NewFeature is defined.
Specifically, when keystate represents NewFeature,
the execution path will hit the second last match arm as before by virtue of
calling as_str on KeyState::NewFeature also yielding "NewFeature".
Explicitly matching on the Unknown variant should
be avoided for two reasons:
- The inner data
UnknownVariantValueis opaque, and no further information can be extracted. - It might inadvertently shadow other intended match arms. Defines the state of a key
Variants (Non-exhaustive)§
This enum is marked as non-exhaustive
CreateComplete
CreateInProgress
DeleteComplete
DeletePending
Unknown(UnknownVariantValue)
Unknown. See the docs on this enum for the correct way to handle unknown variants.Unknown contains new variants that have been added since this code was generated.
Implementations§
Trait Implementations§
source§impl Ord for KeyState
impl Ord for KeyState
source§impl PartialEq for KeyState
impl PartialEq for KeyState
source§impl PartialOrd for KeyState
impl PartialOrd for KeyState
1.0.0 · source§fn le(&self, other: &Rhs) -> bool
fn le(&self, other: &Rhs) -> bool
self and other) and is used by the <=
operator. Read moreimpl Eq for KeyState
impl StructuralPartialEq for KeyState
Auto Trait Implementations§
impl Freeze for KeyState
impl RefUnwindSafe for KeyState
impl Send for KeyState
impl Sync for KeyState
impl Unpin for KeyState
impl UnwindSafe for KeyState
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<Q, K> Comparable<K> for Q
impl<Q, K> Comparable<K> for Q
source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
source§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
key and return true if they are equal.source§impl<T> Instrument for T
impl<T> Instrument for T
source§fn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
source§fn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
source§impl<T> IntoEither for T
impl<T> IntoEither for T
source§fn into_either(self, into_left: bool) -> Either<Self, Self>
fn into_either(self, into_left: bool) -> Either<Self, Self>
self into a Left variant of Either<Self, Self>
if into_left is true.
Converts self into a Right variant of Either<Self, Self>
otherwise. Read moresource§fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
self into a Left variant of Either<Self, Self>
if into_left(&self) returns true.
Converts self into a Right variant of Either<Self, Self>
otherwise. Read more