#[non_exhaustive]pub enum ApplicationState {
Active,
CreateFailed,
Creating,
DeleteFailed,
Deleting,
Unknown(UnknownVariantValue),
}
Expand description
When writing a match expression against ApplicationState
, 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 applicationstate = unimplemented!();
match applicationstate {
ApplicationState::Active => { /* ... */ },
ApplicationState::CreateFailed => { /* ... */ },
ApplicationState::Creating => { /* ... */ },
ApplicationState::DeleteFailed => { /* ... */ },
ApplicationState::Deleting => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when applicationstate
represents
NewFeature
, the execution path will lead to the second last match arm,
even though the enum does not contain a variant ApplicationState::NewFeature
in the current version of SDK. The reason is that the variable other
,
created by the @
operator, is bound to
ApplicationState::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 ApplicationState::NewFeature
is defined.
Specifically, when applicationstate
represents NewFeature
,
the execution path will hit the second last match arm as before by virtue of
calling as_str
on ApplicationState::NewFeature
also yielding "NewFeature"
.
Explicitly matching on the Unknown
variant should
be avoided for two reasons:
- The inner data
UnknownVariantValue
is opaque, and no further information can be extracted. - It might inadvertently shadow other intended match arms.
Variants (Non-exhaustive)§
This enum is marked as non-exhaustive
Active
CreateFailed
Creating
DeleteFailed
Deleting
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§
source§impl ApplicationState
impl ApplicationState
sourcepub fn try_parse(value: &str) -> Result<Self, UnknownVariantError>
pub fn try_parse(value: &str) -> Result<Self, UnknownVariantError>
Parses the enum value while disallowing unknown variants.
Unknown variants will result in an error.
Trait Implementations§
source§impl AsRef<str> for ApplicationState
impl AsRef<str> for ApplicationState
source§impl Clone for ApplicationState
impl Clone for ApplicationState
source§fn clone(&self) -> ApplicationState
fn clone(&self) -> ApplicationState
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl Debug for ApplicationState
impl Debug for ApplicationState
source§impl Display for ApplicationState
impl Display for ApplicationState
source§impl From<&str> for ApplicationState
impl From<&str> for ApplicationState
source§impl FromStr for ApplicationState
impl FromStr for ApplicationState
source§impl Hash for ApplicationState
impl Hash for ApplicationState
source§impl Ord for ApplicationState
impl Ord for ApplicationState
source§fn cmp(&self, other: &ApplicationState) -> Ordering
fn cmp(&self, other: &ApplicationState) -> Ordering
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere
Self: Sized,
source§impl PartialEq for ApplicationState
impl PartialEq for ApplicationState
source§fn eq(&self, other: &ApplicationState) -> bool
fn eq(&self, other: &ApplicationState) -> bool
self
and other
values to be equal, and is used
by ==
.source§impl PartialOrd for ApplicationState
impl PartialOrd for ApplicationState
source§fn partial_cmp(&self, other: &ApplicationState) -> Option<Ordering>
fn partial_cmp(&self, other: &ApplicationState) -> Option<Ordering>
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 ApplicationState
impl StructuralPartialEq for ApplicationState
Auto Trait Implementations§
impl Freeze for ApplicationState
impl RefUnwindSafe for ApplicationState
impl Send for ApplicationState
impl Sync for ApplicationState
impl Unpin for ApplicationState
impl UnwindSafe for ApplicationState
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