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