Enum Volatility 

pub enum Volatility {
    Immutable,
    Volatile,
}

How far a function call’s result can be reused.

Two states, because the engine has two reuse boundaries: a value folded into a cached plan, and a value produced fresh for one execution. A per-statement memoization boundary would need a third state; no such boundary exists, so no third state does either.

Variants

Immutable

Same arguments always give the same result. Foldable at plan time.

Volatile

Can change per call, or has side effects.

Implementations

impl Volatility

pub fn is_foldable(self) -> bool

Whether a call can be folded to a literal at plan time.

pub fn is_volatile(self) -> bool

Whether a call must re-evaluate on every execution.

Trait Implementations

impl Clone for Volatility

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Volatility

impl Debug for Volatility

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

Formats the value using the given formatter.

impl Default for Volatility

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Volatility

impl PartialEq for Volatility

fn eq(&self, other: &Self) -> bool

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Volatility