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