Enum aws_sdk_wafv2::types::PositionalConstraint
source · #[non_exhaustive]pub enum PositionalConstraint {
Contains,
ContainsWord,
EndsWith,
Exactly,
StartsWith,
Unknown(UnknownVariantValue),
}
Expand description
When writing a match expression against PositionalConstraint
, 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 positionalconstraint = unimplemented!();
match positionalconstraint {
PositionalConstraint::Contains => { /* ... */ },
PositionalConstraint::ContainsWord => { /* ... */ },
PositionalConstraint::EndsWith => { /* ... */ },
PositionalConstraint::Exactly => { /* ... */ },
PositionalConstraint::StartsWith => { /* ... */ },
other @ _ if other.as_str() == "NewFeature" => { /* handles a case for `NewFeature` */ },
_ => { /* ... */ },
}
The above code demonstrates that when positionalconstraint
represents
NewFeature
, the execution path will lead to the second last match arm,
even though the enum does not contain a variant PositionalConstraint::NewFeature
in the current version of SDK. The reason is that the variable other
,
created by the @
operator, is bound to
PositionalConstraint::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 PositionalConstraint::NewFeature
is defined.
Specifically, when positionalconstraint
represents NewFeature
,
the execution path will hit the second last match arm as before by virtue of
calling as_str
on PositionalConstraint::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
Contains
ContainsWord
EndsWith
Exactly
StartsWith
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 PositionalConstraint
impl PositionalConstraint
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 PositionalConstraint
impl AsRef<str> for PositionalConstraint
source§impl Clone for PositionalConstraint
impl Clone for PositionalConstraint
source§fn clone(&self) -> PositionalConstraint
fn clone(&self) -> PositionalConstraint
1.0.0 · source§fn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
source
. Read moresource§impl Debug for PositionalConstraint
impl Debug for PositionalConstraint
source§impl Display for PositionalConstraint
impl Display for PositionalConstraint
source§impl From<&str> for PositionalConstraint
impl From<&str> for PositionalConstraint
source§impl FromStr for PositionalConstraint
impl FromStr for PositionalConstraint
source§impl Hash for PositionalConstraint
impl Hash for PositionalConstraint
source§impl Ord for PositionalConstraint
impl Ord for PositionalConstraint
source§fn cmp(&self, other: &PositionalConstraint) -> Ordering
fn cmp(&self, other: &PositionalConstraint) -> 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 PositionalConstraint
impl PartialEq for PositionalConstraint
source§fn eq(&self, other: &PositionalConstraint) -> bool
fn eq(&self, other: &PositionalConstraint) -> bool
self
and other
values to be equal, and is used
by ==
.source§impl PartialOrd for PositionalConstraint
impl PartialOrd for PositionalConstraint
source§fn partial_cmp(&self, other: &PositionalConstraint) -> Option<Ordering>
fn partial_cmp(&self, other: &PositionalConstraint) -> 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 PositionalConstraint
impl StructuralPartialEq for PositionalConstraint
Auto Trait Implementations§
impl Freeze for PositionalConstraint
impl RefUnwindSafe for PositionalConstraint
impl Send for PositionalConstraint
impl Sync for PositionalConstraint
impl Unpin for PositionalConstraint
impl UnwindSafe for PositionalConstraint
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.