Enum BuilderError 

#[non_exhaustive]
pub enum BuilderError {
    MissingField(&'static str),
    Invalid(String),
}

The error a generated builder’s build() returns.

Two cases:

• MissingField — a required field was never set. “Required” is the default; a field is only optional if it carries #[builder(default)] (or #[builder(default = expr)]). This is what lets the builder call out an unset bit/byte instead of silently defaulting it to zero (the gap in the infix with_* API).
• Invalid — a #[bin(validate = …)] soundness check rejected the built value. The string is the validator’s error, stringified, so any Display error type composes without coupling the builder to a protocol-specific error type.

Examples

use bnb::{bitfield, u4, BitsBuilder, BuilderError};

#[bitfield(u8, bits = msb)]
#[derive(BitsBuilder, Clone, Copy, Debug)]
struct Nibbles { hi: u4, lo: u4 }

let err = Nibbles::builder().hi(u4::new(0xA)).build().unwrap_err();
assert_eq!(err, BuilderError::MissingField("lo"));
assert_eq!(err.field(), Some("lo"));
assert_eq!(err.to_string(), "required field `lo` was not set");

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.

MissingField(&'static str)

A required field was not set; carries the field name.

Invalid(String)

A soundness validator rejected the value; carries its message.

Implementations

impl BuilderError

pub fn missing_field(field: &'static str) -> Self

Constructs the “required field not set” error for field.

pub fn invalid(message: impl Into<String>) -> Self

Constructs a soundness-failure error from a validator’s message.

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

The name of the field that was not set, or None for an Invalid error.

Trait Implementations

impl Clone for BuilderError

fn clone(&self) -> BuilderError

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BuilderError

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

Formats the value using the given formatter.

impl Display for BuilderError

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

Formats the value using the given formatter.

impl Eq for BuilderError

impl Error for BuilderError

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 BuilderError

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for BuilderError