Struct ObjectiveEvalError 

pub struct ObjectiveEvalError { /* private fields */ }

A failed objective evaluation, classified by the producer.

Why this carries a typed source

The classification must be made once, by the code that knows what failed, and then travel unchanged. Before this type carried a source, the boundary was lossy: a caller with a rich typed error in hand had to render it to a String to cross into opt, and any layer that later needed to re-classify the same failure had nothing left to consult but the prose. That can produce a real defect: one error variant may be classified recoverable at the site that can still see its type and fatal at the site that could only see its text, so a trial the optimizer is equipped to survive aborts the entire run. The verdict was carried in prose, and prose is one format! away from silently changing meaning.

recoverable_from and fatal_from attach the originating error so downstream code can downcast_ref back to it instead of re-deriving a classification that was already made.

Implementations

impl ObjectiveEvalError

pub fn recoverable(message: impl Into<String>) -> ObjectiveEvalError

A recoverable failure described only by a message.

pub fn fatal(message: impl Into<String>) -> ObjectiveEvalError

A fatal failure described only by a message.

pub fn from_source<E>(kind: ObjectiveEvalKind, source: E) -> ObjectiveEvalError

where E: Error + Send + Sync + 'static,

A failure of the given kind carrying the originating typed error.

The message is the source’s Display; the source itself stays reachable via source_ref / downcast_ref so no later layer has to reconstruct the classification from text.

pub fn recoverable_from<E>(source: E) -> ObjectiveEvalError

where E: Error + Send + Sync + 'static,

from_source with ObjectiveEvalKind::Recoverable.

pub fn fatal_from<E>(source: E) -> ObjectiveEvalError

where E: Error + Send + Sync + 'static,

from_source with ObjectiveEvalKind::Fatal.

pub fn with_context(self, context: impl Display) -> ObjectiveEvalError

Prefix the message, preserving the kind and the typed source.

Use this instead of format!-ing the rendered error into a new ObjectiveEvalError: re-wrapping through a string is exactly what loses the classification.

pub fn kind(&self) -> ObjectiveEvalKind

The producer’s classification.

pub fn is_recoverable(&self) -> bool

true when the solver may back off and continue.

pub fn is_fatal(&self) -> bool

true when the run cannot continue.

pub fn message(&self) -> &str

The message, without the kind prefix Display adds.

pub fn into_message(self) -> String

Consume the error and take its message.

pub fn source_ref(&self) -> Option<&(dyn Error + Send + Sync + 'static)>

The originating error, when one was attached.

pub fn downcast_ref<E>(&self) -> Option<&E>

where E: Error + Send + Sync + 'static,

Recover the producer’s own error type.

This is the mechanism that lets a classification be carried rather than re-derived: a layer that needs to know what failed asks for the type back instead of pattern-matching the prose.

Trait Implementations

impl Clone for ObjectiveEvalError

fn clone(&self) -> ObjectiveEvalError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ObjectiveEvalError

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

Formats the value using the given formatter.

impl Display for ObjectiveEvalError

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

Formats the value using the given formatter.

impl Error for ObjectiveEvalError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.