#[non_exhaustive]pub enum CapacityReservationPreference {
None,
Open,
Unknown(UnknownVariantValue),
}
Expand description
When writing a match expression against CapacityReservationPreference
, 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 capacityreservationpreference = unimplemented!();
match capacityreservationpreference {
CapacityReservationPreference::None => { /* ... */ },
CapacityReservationPreference::Open => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when capacityreservationpreference
represents
NewFeature
, the execution path will lead to the second last match arm,
even though the enum does not contain a variant CapacityReservationPreference::NewFeature
in the current version of SDK. The reason is that the variable other
,
created by the @
operator, is bound to
CapacityReservationPreference::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 CapacityReservationPreference::NewFeature
is defined.
Specifically, when capacityreservationpreference
represents NewFeature
,
the execution path will hit the second last match arm as before by virtue of
calling as_str
on CapacityReservationPreference::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
None
Open
Unknown(UnknownVariantValue)
Unknown
contains new variants that have been added since this code was generated.
Implementations§
Trait Implementations§
source§impl AsRef<str> for CapacityReservationPreference
impl AsRef<str> for CapacityReservationPreference
source§impl Clone for CapacityReservationPreference
impl Clone for CapacityReservationPreference
source§fn clone(&self) -> CapacityReservationPreference
fn clone(&self) -> CapacityReservationPreference
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl From<&str> for CapacityReservationPreference
impl From<&str> for CapacityReservationPreference
source§impl Hash for CapacityReservationPreference
impl Hash for CapacityReservationPreference
source§impl Ord for CapacityReservationPreference
impl Ord for CapacityReservationPreference
source§fn cmp(&self, other: &CapacityReservationPreference) -> Ordering
fn cmp(&self, other: &CapacityReservationPreference) -> Ordering
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere Self: Sized,
source§impl PartialEq<CapacityReservationPreference> for CapacityReservationPreference
impl PartialEq<CapacityReservationPreference> for CapacityReservationPreference
source§fn eq(&self, other: &CapacityReservationPreference) -> bool
fn eq(&self, other: &CapacityReservationPreference) -> bool
self
and other
values to be equal, and is used
by ==
.source§impl PartialOrd<CapacityReservationPreference> for CapacityReservationPreference
impl PartialOrd<CapacityReservationPreference> for CapacityReservationPreference
source§fn partial_cmp(&self, other: &CapacityReservationPreference) -> Option<Ordering>
fn partial_cmp(&self, other: &CapacityReservationPreference) -> 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 CapacityReservationPreference
impl StructuralEq for CapacityReservationPreference
impl StructuralPartialEq for CapacityReservationPreference
Auto Trait Implementations§
impl RefUnwindSafe for CapacityReservationPreference
impl Send for CapacityReservationPreference
impl Sync for CapacityReservationPreference
impl Unpin for CapacityReservationPreference
impl UnwindSafe for CapacityReservationPreference
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> Equivalent<K> for Qwhere
Q: Eq + ?Sized,
K: Borrow<Q> + ?Sized,
impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,
source§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
key
and return true
if they are equal.