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