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