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