Trait std::error::Error1.0.0 [−] [src]

pub trait Error: Debug + Display {
    fn description(&self) -> &str;

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

Base functionality for all errors in Rust.

Required Methods

A short description of the error.

The description should only be used for a simple message. It should not contain newlines or sentence-ending punctuation, to facilitate embedding in larger user-facing strings. For showing formatted error messages with more information see Display.

Examples

use std::error::Error;

match "xc".parse::<u32>() {
    Err(e) => {
        println!("Error: {}", e.description());
    }
    _ => println!("No error"),
}Run

Provided Methods

The lower-level cause 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 description(&self) -> &str {
        "I'm the superhero of errors"
    }

    fn cause(&self) -> Option<&Error> {
        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 description(&self) -> &str {
        "I'm SuperError side kick"
    }
}

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

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

Methods

impl Error + 'static
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Returns true if the boxed type is the same as T

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

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

impl Error + Send + 'static
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Forwards to the method defined on the type Any.

Forwards to the method defined on the type Any.

Forwards to the method defined on the type Any.

impl Error + Send + Sync + 'static
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Forwards to the method defined on the type Any.

Forwards to the method defined on the type Any.

Forwards to the method defined on the type Any.

impl Error
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Attempt to downcast the box to a concrete type.

impl Error + Send
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Attempt to downcast the box to a concrete type.

impl Error + Send + Sync
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Attempt to downcast the box to a concrete type.

Implementations on Foreign Types

impl Error for AllocErr
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impl Error for CannotReallocInPlace
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impl Error for TryFromSliceError
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Implementors