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