Enum Error 

#[non_exhaustive]
pub enum Error {
    UnsignedVarintDecode {
        source: Error,
    },
    InsufficientData {
        expected: usize,
        actual: usize,
    },
    InvalidEncoding {
        reason: String,
    },
}

Errors generated by the numeric type impls

This error type follows Rust error handling best practices:

• Uses #[non_exhaustive] to allow adding new variants without breaking changes
• Provides structured error variants with context information
• Implements proper error source chains via #[source] attribute
• Uses thiserror for ergonomic error handling

Error Source Chains

Errors that wrap other errors (like UnsignedVarintDecode) properly implement the Error::source() method, allowing error chains to be inspected for debugging.

Examples

use multi_trait::{TryDecodeFrom, Error};

// Attempting to decode from empty slice returns an error
let result = u8::try_decode_from(&[]);
assert!(result.is_err());

// The error provides context about what went wrong
if let Err(e) = result {
    eprintln!("Decode failed: {}", e);
    // In production code with std, you can access the error source:
    // if let Some(source) = std::error::Error::source(&e) {
    //     eprintln!("Caused by: {}", source);
    // }
}

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.

UnsignedVarintDecode

Failed to decode unsigned varint data

This error occurs when the underlying unsigned-varint decoder fails. Common causes include:

• Truncated varint data (incomplete bytes)
• Invalid varint encoding
• Buffer underflow

The source error provides additional details about the specific failure.

Fields

source: Error

The underlying decode error from unsigned-varint crate

InsufficientData

Insufficient data to decode value

This error occurs when the input slice doesn’t contain enough bytes to decode the requested type. This typically happens with truncated data.

Examples

use multi_trait::{TryDecodeFrom, Error};

// Empty slice cannot decode any value
let result = u16::try_decode_from(&[]);
match result {
    Err(Error::UnsignedVarintDecode { .. }) => {
        // Expected behavior for empty input
    }
    _ => panic!("Unexpected result"),
}

Fields

expected: usize

Expected number of bytes needed

actual: usize

Actual number of bytes available in the input

InvalidEncoding

Invalid encoding encountered

This error occurs when the data is structurally invalid beyond just varint decoding issues. For example, if a value is out of range for the target type or violates format-specific constraints.

This variant is provided for future extensibility and custom validation logic.

Fields

reason: String

Human-readable description of why the encoding is invalid

Trait Implementations

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, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

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.