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