#[non_exhaustive]pub enum QueryExecutionMode {
Auto,
Manual,
Unknown(UnknownVariantValue),
}
Expand description
When writing a match expression against QueryExecutionMode
, 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 queryexecutionmode = unimplemented!();
match queryexecutionmode {
QueryExecutionMode::Auto => { /* ... */ },
QueryExecutionMode::Manual => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when queryexecutionmode
represents
NewFeature
, the execution path will lead to the second last match arm,
even though the enum does not contain a variant QueryExecutionMode::NewFeature
in the current version of SDK. The reason is that the variable other
,
created by the @
operator, is bound to
QueryExecutionMode::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 QueryExecutionMode::NewFeature
is defined.
Specifically, when queryexecutionmode
represents NewFeature
,
the execution path will hit the second last match arm as before by virtue of
calling as_str
on QueryExecutionMode::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
Auto
Manual
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 QueryExecutionMode
impl QueryExecutionMode
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 QueryExecutionMode
impl AsRef<str> for QueryExecutionMode
source§impl Clone for QueryExecutionMode
impl Clone for QueryExecutionMode
source§fn clone(&self) -> QueryExecutionMode
fn clone(&self) -> QueryExecutionMode
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl Debug for QueryExecutionMode
impl Debug for QueryExecutionMode
source§impl Display for QueryExecutionMode
impl Display for QueryExecutionMode
source§impl From<&str> for QueryExecutionMode
impl From<&str> for QueryExecutionMode
source§impl FromStr for QueryExecutionMode
impl FromStr for QueryExecutionMode
source§impl Hash for QueryExecutionMode
impl Hash for QueryExecutionMode
source§impl Ord for QueryExecutionMode
impl Ord for QueryExecutionMode
source§fn cmp(&self, other: &QueryExecutionMode) -> Ordering
fn cmp(&self, other: &QueryExecutionMode) -> 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 QueryExecutionMode
impl PartialEq for QueryExecutionMode
source§impl PartialOrd for QueryExecutionMode
impl PartialOrd for QueryExecutionMode
impl Eq for QueryExecutionMode
impl StructuralPartialEq for QueryExecutionMode
Auto Trait Implementations§
impl Freeze for QueryExecutionMode
impl RefUnwindSafe for QueryExecutionMode
impl Send for QueryExecutionMode
impl Sync for QueryExecutionMode
impl Unpin for QueryExecutionMode
impl UnwindSafe for QueryExecutionMode
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<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)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