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