Struct Error 

pub struct Error { /* private fields */ }

An error, with everything a caller or an agent needs to act on it.

Cheap to construct on the failure path and never constructed on the success path, so the size of this type does not touch the hot path. It is returned by value rather than boxed because a boxed error means an allocation, and an allocation on a shard thread aborts (yo-alloc).

Implementations

impl Error

pub fn new(code: Code, message: impl Into<String>) -> Error

A new error with just a message.

The message is copied into a String here, and that allocation is wrapped in yo_alloc::allow because a shard thread that allocates aborts and an error is by definition off the path the budget is for. A client that sends INCR at a key holding a word should get an error back, not a server that stops answering everybody else.

The wrap only covers what happens inside this call, so a caller that builds its message with format! first has already allocated by the time it gets here. Use Error::fmt for those.

pub fn fmt(code: Code, args: Arguments<'_>) -> Error

A new error whose message needs formatting, built without allocating outside the wrap.

Error::fmt(code, format_args!("no such thing: {name}")) is the shape. format_args! builds nothing, so the only allocation is the one this does, and it happens where it is allowed to.

pub fn at(self, position: u32) -> Error

Attach the argument index or byte offset the error is about.

P10: the first error should teach. A position turns “invalid arguments” into “argument 3 is invalid”, which is the difference between a user reading the docs and a user guessing.

pub fn with_detail(self, detail: impl Into<String>) -> Error

Attach machine readable detail, such as errno=13 path=/var/lib/app.yo.

pub const fn code(&self) -> Code

The stable condition code.

pub const fn is_retryable(&self) -> bool

Whether the identical call could succeed later.

pub fn message(&self) -> &str

The human readable message, without the code or the URL.

pub const fn position(&self) -> Option<u32>

The argument index or byte offset, if the error is about one.

pub fn detail(&self) -> Option<&str>

Machine readable detail, if any.

pub fn url(&self) -> Option<&'static str>

The documentation page for this condition, if it has one.

Trait Implementations

impl Clone for Error

fn clone(&self) -> Error

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Eq for Error

impl Error for Error

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.

impl PartialEq for Error

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Error