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