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