#[non_exhaustive]pub enum AllowsMultipleInstanceTypes {
Off,
On,
Unknown(UnknownVariantValue),
}Expand description
When writing a match expression against AllowsMultipleInstanceTypes, 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 allowsmultipleinstancetypes = unimplemented!();
match allowsmultipleinstancetypes {
AllowsMultipleInstanceTypes::Off => { /* ... */ },
AllowsMultipleInstanceTypes::On => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when allowsmultipleinstancetypes represents
NewFeature, the execution path will lead to the second last match arm,
even though the enum does not contain a variant AllowsMultipleInstanceTypes::NewFeature
in the current version of SDK. The reason is that the variable other,
created by the @ operator, is bound to
AllowsMultipleInstanceTypes::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 AllowsMultipleInstanceTypes::NewFeature is defined.
Specifically, when allowsmultipleinstancetypes represents NewFeature,
the execution path will hit the second last match arm as before by virtue of
calling as_str on AllowsMultipleInstanceTypes::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.
Variants (Non-exhaustive)§
This enum is marked as non-exhaustive
Off
On
Unknown(UnknownVariantValue)
Unknown contains new variants that have been added since this code was generated.
Implementations§
Trait Implementations§
source§impl AsRef<str> for AllowsMultipleInstanceTypes
impl AsRef<str> for AllowsMultipleInstanceTypes
source§impl Clone for AllowsMultipleInstanceTypes
impl Clone for AllowsMultipleInstanceTypes
source§fn clone(&self) -> AllowsMultipleInstanceTypes
fn clone(&self) -> AllowsMultipleInstanceTypes
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source. Read moresource§impl Debug for AllowsMultipleInstanceTypes
impl Debug for AllowsMultipleInstanceTypes
source§impl From<&str> for AllowsMultipleInstanceTypes
impl From<&str> for AllowsMultipleInstanceTypes
source§impl Hash for AllowsMultipleInstanceTypes
impl Hash for AllowsMultipleInstanceTypes
source§impl Ord for AllowsMultipleInstanceTypes
impl Ord for AllowsMultipleInstanceTypes
source§fn cmp(&self, other: &AllowsMultipleInstanceTypes) -> Ordering
fn cmp(&self, other: &AllowsMultipleInstanceTypes) -> Ordering
1.21.0 · source§fn max(self, other: Self) -> Selfwhere
Self: Sized,
fn max(self, other: Self) -> Selfwhere Self: Sized,
source§impl PartialEq<AllowsMultipleInstanceTypes> for AllowsMultipleInstanceTypes
impl PartialEq<AllowsMultipleInstanceTypes> for AllowsMultipleInstanceTypes
source§fn eq(&self, other: &AllowsMultipleInstanceTypes) -> bool
fn eq(&self, other: &AllowsMultipleInstanceTypes) -> bool
self and other values to be equal, and is used
by ==.source§impl PartialOrd<AllowsMultipleInstanceTypes> for AllowsMultipleInstanceTypes
impl PartialOrd<AllowsMultipleInstanceTypes> for AllowsMultipleInstanceTypes
source§fn partial_cmp(&self, other: &AllowsMultipleInstanceTypes) -> Option<Ordering>
fn partial_cmp(&self, other: &AllowsMultipleInstanceTypes) -> 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 AllowsMultipleInstanceTypes
impl StructuralEq for AllowsMultipleInstanceTypes
impl StructuralPartialEq for AllowsMultipleInstanceTypes
Auto Trait Implementations§
impl RefUnwindSafe for AllowsMultipleInstanceTypes
impl Send for AllowsMultipleInstanceTypes
impl Sync for AllowsMultipleInstanceTypes
impl Unpin for AllowsMultipleInstanceTypes
impl UnwindSafe for AllowsMultipleInstanceTypes
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.