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