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