Struct MaybeValue 

pub struct MaybeValue<V>(/* private fields */);

A value that may or may not be present.

This is the Rust counterpart of FusionCache’s MaybeValue<T>. It is a thin, purpose-named wrapper around Option so the public API reads the same as FusionCache (has_value, value_or_default, from_value, …) while still interoperating freely with idiomatic Option via From.

It appears in two places:

• the return type of Cache::try_get — a miss is MaybeValue::none, distinct from “present but None/null”;
• the fail_safe_default argument of Cache::get_or_set — a last-resort value used only when the factory fails and no stale entry exists.

Implementations

impl<V> MaybeValue<V>

pub fn from_value(value: V) -> Self

A present value.

pub fn none() -> Self

The absence of a value.

pub fn has_value(&self) -> bool

true if a value is present.

pub fn value(&self) -> Option<&V>

Borrows the contained value, if any.

pub fn into_value(self) -> Option<V>

Consumes the wrapper, returning the contained value, if any.

pub fn value_or(self, default: V) -> V

Returns the contained value or default when absent.

pub fn map<U, F: FnOnce(V) -> U>(self, f: F) -> MaybeValue<U>

Maps the contained value, preserving absence.

impl<V: Clone> MaybeValue<V>

pub fn value_or_clone(&self, default: V) -> V

Returns a clone of the contained value or default when absent.

impl<V: Default> MaybeValue<V>

pub fn value_or_default(self) -> V

Returns the contained value or V::default() when absent.

Trait Implementations

impl<V: Clone> Clone for MaybeValue<V>

fn clone(&self) -> MaybeValue<V>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<V: Debug> Debug for MaybeValue<V>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<V> Default for MaybeValue<V>

fn default() -> Self

The default is MaybeValue::none, matching default(MaybeValue<T>).

impl<V: Eq> Eq for MaybeValue<V>

impl<V> From<MaybeValue<V>> for Option<V>

fn from(maybe: MaybeValue<V>) -> Self

Converts to this type from the input type.

impl<V> From<Option<V>> for MaybeValue<V>

fn from(option: Option<V>) -> Self

Converts to this type from the input type.

impl<V> From<V> for MaybeValue<V>

fn from(value: V) -> Self

Converts to this type from the input type.

impl<V: PartialEq> PartialEq for MaybeValue<V>

fn eq(&self, other: &MaybeValue<V>) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<V: PartialEq> StructuralPartialEq for MaybeValue<V>