Struct snafu::Whatever

pub struct Whatever { /* private fields */ }

A basic error type that you can use as a first step to better error handling.

You can use this type in your own application as a quick way to create errors or add basic context to another error. This can also be used in a library, but consider wrapping it in an opaque error to avoid putting the SNAFU crate in your public API.

Examples

use snafu::prelude::*;

type Result<T, E = snafu::Whatever> = std::result::Result<T, E>;

fn subtract_numbers(a: u32, b: u32) -> Result<u32> {
    if a > b {
        Ok(a - b)
    } else {
        whatever!("Can't subtract {} - {}", a, b)
    }
}

fn complicated_math(a: u32, b: u32) -> Result<u32> {
    let val = subtract_numbers(a, b).whatever_context("Can't do the math")?;
    Ok(val * 2)
}

See whatever! for detailed usage instructions.

Limitations

When wrapping errors, only the backtrace from the shallowest function is guaranteed to be available. If you need the deepest possible trace, consider creating a custom error type and using #[snafu(backtrace)] on the source field. If a best-effort attempt is sufficient, see the backtrace method.

When the standard library stabilizes backtrace support, this behavior may change.

Implementations

impl Whatever

pub fn backtrace(&self) -> Option<&Backtrace>

Gets the backtrace from the deepest Whatever error. If none of the underlying errors are Whatever, returns the backtrace from when this instance was created.

Trait Implementations

impl Debug for Whatever

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

Formats the value using the given formatter.

impl Display for Whatever

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

Formats the value using the given formatter.

impl Error for Whateverwhere
    Self: Debug + Display,

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

The lower-level source of this error, if any.

fn provide<'a>(&'a self, demand: &mut Demand<'a>)

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

Provides type based access to context intended for error reports.

impl ErrorCompat for Whatever

fn backtrace(&self) -> Option<&Backtrace>

Returns a Backtrace that may be printed.

fn iter_chain(&self) -> ChainCompat<'_> where
    Self: AsErrorSource,

Returns an iterator for traversing the chain of errors, starting with the current error and continuing with recursive calls to Error::source.

impl FromString for Whatever

type Source = Box<dyn Error + 'static, Global>

The underlying error

fn without_source(message: String) -> Self

Create a brand new error from the given string

fn with_source(error: Self::Source, message: String) -> Self

Wrap an existing error with the given string