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