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