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