#[non_exhaustive]pub enum S3MetadataDirective {
Copy,
Replace,
Unknown(UnknownVariantValue),
}
Expand description
When writing a match expression against S3MetadataDirective
, 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 s3metadatadirective = unimplemented!();
match s3metadatadirective {
S3MetadataDirective::Copy => { /* ... */ },
S3MetadataDirective::Replace => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when s3metadatadirective
represents
NewFeature
, the execution path will lead to the second last match arm,
even though the enum does not contain a variant S3MetadataDirective::NewFeature
in the current version of SDK. The reason is that the variable other
,
created by the @
operator, is bound to
S3MetadataDirective::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 S3MetadataDirective::NewFeature
is defined.
Specifically, when s3metadatadirective
represents NewFeature
,
the execution path will hit the second last match arm as before by virtue of
calling as_str
on S3MetadataDirective::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
Copy
Replace
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 S3MetadataDirective
impl S3MetadataDirective
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 S3MetadataDirective
impl AsRef<str> for S3MetadataDirective
source§impl Clone for S3MetadataDirective
impl Clone for S3MetadataDirective
source§fn clone(&self) -> S3MetadataDirective
fn clone(&self) -> S3MetadataDirective
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl Debug for S3MetadataDirective
impl Debug for S3MetadataDirective
source§impl Display for S3MetadataDirective
impl Display for S3MetadataDirective
source§impl From<&str> for S3MetadataDirective
impl From<&str> for S3MetadataDirective
source§impl FromStr for S3MetadataDirective
impl FromStr for S3MetadataDirective
source§impl Hash for S3MetadataDirective
impl Hash for S3MetadataDirective
source§impl Ord for S3MetadataDirective
impl Ord for S3MetadataDirective
source§fn cmp(&self, other: &S3MetadataDirective) -> Ordering
fn cmp(&self, other: &S3MetadataDirective) -> 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 S3MetadataDirective
impl PartialEq for S3MetadataDirective
source§fn eq(&self, other: &S3MetadataDirective) -> bool
fn eq(&self, other: &S3MetadataDirective) -> bool
self
and other
values to be equal, and is used
by ==
.source§impl PartialOrd for S3MetadataDirective
impl PartialOrd for S3MetadataDirective
source§fn partial_cmp(&self, other: &S3MetadataDirective) -> Option<Ordering>
fn partial_cmp(&self, other: &S3MetadataDirective) -> 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 S3MetadataDirective
impl StructuralPartialEq for S3MetadataDirective
Auto Trait Implementations§
impl Freeze for S3MetadataDirective
impl RefUnwindSafe for S3MetadataDirective
impl Send for S3MetadataDirective
impl Sync for S3MetadataDirective
impl Unpin for S3MetadataDirective
impl UnwindSafe for S3MetadataDirective
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
source§impl<Q, K> Comparable<K> for Q
impl<Q, K> Comparable<K> for Q
source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
source§impl<Q, K> Equivalent<K> for Q
impl<Q, K> Equivalent<K> for Q
source§fn equivalent(&self, key: &K) -> bool
fn equivalent(&self, key: &K) -> bool
key
and return true
if they are equal.source§impl<T> Instrument for T
impl<T> Instrument for T
source§fn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
source§fn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
source§impl<T> IntoEither for T
impl<T> IntoEither for T
source§fn into_either(self, into_left: bool) -> Either<Self, Self>
fn into_either(self, into_left: bool) -> Either<Self, Self>
self
into a Left
variant of Either<Self, Self>
if into_left
is true
.
Converts self
into a Right
variant of Either<Self, Self>
otherwise. Read moresource§fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
self
into a Left
variant of Either<Self, Self>
if into_left(&self)
returns true
.
Converts self
into a Right
variant of Either<Self, Self>
otherwise. Read more