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