Trait ockam_core::lib::error::Error1.0.0[−][src]

pub trait Error: Debug + Display {
    fn source(&self) -> Option<&(dyn Error + 'static)> { ... }

    fn backtrace(&self) -> Option<&Backtrace> { ... }

    fn description(&self) -> &str { ... }

    fn cause(&self) -> Option<&dyn Error> { ... }
}
Expand description

Error is a trait representing the basic expectations for error values, i.e., values of type E in Result<T, E>.

Errors must describe themselves through the Display and Debug traits. Error messages are typically concise lowercase sentences without trailing punctuation:

let err = "NaN".parse::<u32>().unwrap_err();
assert_eq!(err.to_string(), "invalid digit found in string");

Errors may provide cause chain information. Error::source() is generally used when errors cross “abstraction boundaries”. If one module must report an error that is caused by an error from a lower-level module, it can allow accessing that error via Error::source(). This makes it possible for the high-level module to provide its own errors while also revealing some of the implementation for debugging via source chains.

Provided methods

fn source(&self) -> Option<&(dyn Error + 'static)>1.30.0[src]

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

Examples

use std::error::Error;
use std::fmt;

#[derive(Debug)]
struct SuperError {
    side: SuperErrorSideKick,
}

impl fmt::Display for SuperError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "SuperError is here!")
    }
}

impl Error for SuperError {
    fn source(&self) -> Option<&(dyn Error + 'static)> {
        Some(&self.side)
    }
}

#[derive(Debug)]
struct SuperErrorSideKick;

impl fmt::Display for SuperErrorSideKick {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "SuperErrorSideKick is here!")
    }
}

impl Error for SuperErrorSideKick {}

fn get_super_error() -> Result<(), SuperError> {
    Err(SuperError { side: SuperErrorSideKick })
}

fn main() {
    match get_super_error() {
        Err(e) => {
            println!("Error: {}", e);
            println!("Caused by: {}", e.source().unwrap());
        }
        _ => println!("No error"),
    }
}

fn backtrace(&self) -> Option<&Backtrace>[src]

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

Returns a stack backtrace, if available, of where this error occurred.

This function allows inspecting the location, in code, of where an error happened. The returned Backtrace contains information about the stack trace of the OS thread of execution of where the error originated from.

Note that not all errors contain a Backtrace. Also note that a Backtrace may actually be empty. For more information consult the Backtrace type itself.

fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

if let Err(e) = "xc".parse::<u32>() {
    // Print `e` itself, no need for description().
    eprintln!("Error: {}", e);
}

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

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

Implementations

impl dyn Error + 'static[src]

pub fn is<T>(&self) -> bool where
    T: 'static + Error, 1.3.0[src]

Returns true if the boxed type is the same as T

pub fn downcast_ref<T>(&self) -> Option<&T> where
    T: 'static + Error, 1.3.0[src]

Returns some reference to the boxed value if it is of type T, or None if it isn’t.

pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
    T: 'static + Error, 1.3.0[src]

Returns some mutable reference to the boxed value if it is of type T, or None if it isn’t.

impl dyn Error + 'static + Send[src]

pub fn is<T>(&self) -> bool where
    T: 'static + Error, 1.3.0[src]

Forwards to the method defined on the type dyn Error.

pub fn downcast_ref<T>(&self) -> Option<&T> where
    T: 'static + Error, 1.3.0[src]

Forwards to the method defined on the type dyn Error.

pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
    T: 'static + Error, 1.3.0[src]

Forwards to the method defined on the type dyn Error.

impl dyn Error + 'static + Sync + Send[src]

pub fn is<T>(&self) -> bool where
    T: 'static + Error, 1.3.0[src]

Forwards to the method defined on the type dyn Error.

pub fn downcast_ref<T>(&self) -> Option<&T> where
    T: 'static + Error, 1.3.0[src]

Forwards to the method defined on the type dyn Error.

pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
    T: 'static + Error, 1.3.0[src]

Forwards to the method defined on the type dyn Error.

impl dyn Error + 'static[src]

pub fn downcast<T>(
    self: Box<dyn Error + 'static, Global>
) -> Result<Box<T, Global>, Box<dyn Error + 'static, Global>> where
    T: 'static + Error, 1.3.0[src]

Attempts to downcast the box to a concrete type.

pub fn chain(&self) -> Chain<'_>ⓘ

Notable traits for Chain<'a>

impl<'a> Iterator for Chain<'a> type Item = &'a (dyn Error + 'static);
[src]

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

Returns an iterator starting with the current error and continuing with recursively calling Error::source.

If you want to omit the current error and only use its sources, use skip(1).

Examples

#![feature(error_iter)]
use std::error::Error;
use std::fmt;

#[derive(Debug)]
struct A;

#[derive(Debug)]
struct B(Option<Box<dyn Error + 'static>>);

impl fmt::Display for A {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "A")
    }
}

impl fmt::Display for B {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "B")
    }
}

impl Error for A {}

impl Error for B {
    fn source(&self) -> Option<&(dyn Error + 'static)> {
        self.0.as_ref().map(|e| e.as_ref())
    }
}

let b = B(Some(Box::new(A)));

// let err : Box<Error> = b.into(); // or
let err = &b as &(dyn Error);

let mut iter = err.chain();

assert_eq!("B".to_string(), iter.next().unwrap().to_string());
assert_eq!("A".to_string(), iter.next().unwrap().to_string());
assert!(iter.next().is_none());
assert!(iter.next().is_none());

impl dyn Error + 'static + Send[src]

pub fn downcast<T>(
    self: Box<dyn Error + 'static + Send, Global>
) -> Result<Box<T, Global>, Box<dyn Error + 'static + Send, Global>> where
    T: 'static + Error, 1.3.0[src]

Attempts to downcast the box to a concrete type.

impl dyn Error + 'static + Sync + Send[src]

pub fn downcast<T>(
    self: Box<dyn Error + 'static + Sync + Send, Global>
) -> Result<Box<T, Global>, Box<dyn Error + 'static + Sync + Send, Global>> where
    T: 'static + Error, 1.3.0[src]

Attempts to downcast the box to a concrete type.

Implementations on Foreign Types

impl Error for RecvTimeoutError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<T> Error for PoisonError<T>[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<T> Error for SendError<T> where
    T: Send, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for TryReserveError[src]

impl Error for SystemTimeError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for RecvError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<'a, K, V> Error for OccupiedError<'a, K, V> where
    K: Debug,
    V: Debug, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for TryRecvError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for BorrowMutError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for ParseCharError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for AccessError[src]

impl<'a, T> Error for &'a T where
    T: Error + ?Sized, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

pub fn cause(&self) -> Option<&dyn Error>[src]

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]

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

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

impl Error for LayoutError[src]

impl Error for AllocError[src]

impl Error for BorrowError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for CharTryFromError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<'a, K, V> Error for OccupiedError<'a, K, V> where
    K: Debug + Ord,
    V: Debug, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for JoinPathsError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for FromUtf16Error[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for FromBytesWithNulError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for VarError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for ExitStatusError[src]

impl Error for IntoStringError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]

impl<T> Error for Arc<T> where
    T: Error + ?Sized, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

pub fn cause(&self) -> Option<&dyn Error>[src]

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]

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

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

impl Error for DecodeUtf16Error[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<W> Error for IntoInnerError<W> where
    W: Send + Debug, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<T> Error for TryLockError<T>[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

pub fn cause(&self) -> Option<&dyn Error>[src]

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

impl Error for Error[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

pub fn cause(&self) -> Option<&dyn Error>[src]

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]

impl Error for FromUtf8Error[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for FromVecWithNulError[src]

impl Error for ![src]

impl Error for NulError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<T> Error for TrySendError<T> where
    T: Send, [src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for TryFromSliceError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for StripPrefixError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for Error[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for Error[src]

impl Error for FromHexError[src]

impl Error for WeightedError[src]

impl Error for BernoulliError[src]

impl Error for ReadError[src]

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]

impl Error for Error[src]

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]

impl Error for Error[src]

Implementors

impl Error for Infallible1.8.0[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for ockam_core::Error[src]

impl Error for ockam_core::lib::fmt::Error1.11.0[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for AddrParseError1.4.0[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for ParseFloatError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for ParseIntError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for TryFromIntError1.34.0[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for ParseBoolError[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl Error for Utf8Error[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

impl<T> Error for Box<T, Global> where
    T: Error, 1.8.0[src]

pub fn description(&self) -> &str[src]

👎 Deprecated since 1.42.0:

use the Display impl or to_string()

pub fn cause(&self) -> Option<&dyn Error>[src]

👎 Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

pub fn source(&self) -> Option<&(dyn Error + 'static)>[src]