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