Enum ObserverMode 

#[non_exhaustive]
pub enum ObserverMode {
    Never,
    Always,
    Every(u64),
    NewBest,
}

Per-registration policy for observe_iter.

Every variant gates the iteration callback only: observe_init and observe_final always fire. A user who wants to fully disable an observer should simply not register it. The same policy applies to ObserveSolver and ObservationEvent::Iter callbacks.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Never

Skip observe_iter entirely. The observer still sees observe_init/observe_final.

Always

Fire observe_iter on every iteration.

Every(u64)

Fire observe_iter on iterations whose (post-increment) counter is a multiple of n. Every(1) is equivalent to Always; Every(0) is rejected as nonsensical and panics on construction via every, but raw construction is permitted and treated as Never (no iter is a multiple of zero under the iter % n == 0 rule because n == 0 would divide-by-zero; the executor checks for n != 0 before the modulus).

NewBest

Fire observe_iter only on iterations that strictly improved the best cost so far, i.e. where State::best_iter equals State::iter. Ties (a new iterate merely equal to the incumbent) do not fire, matching the strict < test in State::update_best.

Pairs naturally with observers that only care about progress, such as logging or checkpointing the incumbent whenever it moves.

Implementations

impl ObserverMode

pub fn every(n: u64) -> Self

Construct an Every(n) mode, panicking when n == 0.

Prefer this over the raw variant when n comes from user input.

Trait Implementations

impl Clone for ObserverMode

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 ObserverMode

impl Debug for ObserverMode

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

Formats the value using the given formatter.

impl Eq for ObserverMode

impl PartialEq for ObserverMode

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ObserverMode