Enum aws_sdk_glue::types::ExistCondition
source · #[non_exhaustive]pub enum ExistCondition {
MustExist,
None,
NotExist,
Unknown(UnknownVariantValue),
}
Expand description
When writing a match expression against ExistCondition
, 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 existcondition = unimplemented!();
match existcondition {
ExistCondition::MustExist => { /* ... */ },
ExistCondition::None => { /* ... */ },
ExistCondition::NotExist => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when existcondition
represents
NewFeature
, the execution path will lead to the second last match arm,
even though the enum does not contain a variant ExistCondition::NewFeature
in the current version of SDK. The reason is that the variable other
,
created by the @
operator, is bound to
ExistCondition::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 ExistCondition::NewFeature
is defined.
Specifically, when existcondition
represents NewFeature
,
the execution path will hit the second last match arm as before by virtue of
calling as_str
on ExistCondition::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
MustExist
None
NotExist
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 ExistCondition
impl ExistCondition
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 ExistCondition
impl AsRef<str> for ExistCondition
source§impl Clone for ExistCondition
impl Clone for ExistCondition
source§fn clone(&self) -> ExistCondition
fn clone(&self) -> ExistCondition
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl Debug for ExistCondition
impl Debug for ExistCondition
source§impl Display for ExistCondition
impl Display for ExistCondition
source§impl From<&str> for ExistCondition
impl From<&str> for ExistCondition
source§impl FromStr for ExistCondition
impl FromStr for ExistCondition
source§impl Hash for ExistCondition
impl Hash for ExistCondition
source§impl Ord for ExistCondition
impl Ord for ExistCondition
source§fn cmp(&self, other: &ExistCondition) -> Ordering
fn cmp(&self, other: &ExistCondition) -> 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 ExistCondition
impl PartialEq for ExistCondition
source§fn eq(&self, other: &ExistCondition) -> bool
fn eq(&self, other: &ExistCondition) -> bool
self
and other
values to be equal, and is used
by ==
.source§impl PartialOrd for ExistCondition
impl PartialOrd for ExistCondition
source§fn partial_cmp(&self, other: &ExistCondition) -> Option<Ordering>
fn partial_cmp(&self, other: &ExistCondition) -> 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 ExistCondition
impl StructuralPartialEq for ExistCondition
Auto Trait Implementations§
impl Freeze for ExistCondition
impl RefUnwindSafe for ExistCondition
impl Send for ExistCondition
impl Sync for ExistCondition
impl Unpin for ExistCondition
impl UnwindSafe for ExistCondition
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