Trait std_tools::ErrorInterface
1.0.0 · source · [−]pub trait ErrorInterface: 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
The lower-level source of this error, if any.
Examples
use std::error::Error;
use std::fmt;
#[derive(Debug)]
struct SuperError {
source: 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.source)
}
}
#[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 { source: SuperErrorSideKick })
}
fn main() {
match get_super_error() {
Err(e) => {
println!("Error: {e}");
println!("Caused by: {}", e.source().unwrap());
}
_ => println!("No error"),
}
}
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
fn description(&self) -> &str
use the Display impl or to_string()
if let Err(e) = "xc".parse::<u32>() {
// Print `e` itself, no need for description().
eprintln!("Error: {e}");
}
Implementations
sourceimpl dyn Error + 'static
impl dyn Error + 'static
1.3.0 · sourcepub fn is<T>(&self) -> bool where
T: 'static + Error,
pub fn is<T>(&self) -> bool where
T: 'static + Error,
Returns true
if the inner type is the same as T
.
1.3.0 · sourcepub fn downcast_ref<T>(&self) -> Option<&T> where
T: 'static + Error,
pub fn downcast_ref<T>(&self) -> Option<&T> where
T: 'static + Error,
Returns some reference to the inner value if it is of type T
, or
None
if it isn’t.
1.3.0 · sourcepub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
T: 'static + Error,
pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
T: 'static + Error,
Returns some mutable reference to the inner value if it is of type T
, or
None
if it isn’t.
sourceimpl dyn Error + Send + 'static
impl dyn Error + Send + 'static
1.3.0 · sourcepub fn is<T>(&self) -> bool where
T: 'static + Error,
pub fn is<T>(&self) -> bool where
T: 'static + Error,
Forwards to the method defined on the type dyn Error
.
1.3.0 · sourcepub fn downcast_ref<T>(&self) -> Option<&T> where
T: 'static + Error,
pub fn downcast_ref<T>(&self) -> Option<&T> where
T: 'static + Error,
Forwards to the method defined on the type dyn Error
.
1.3.0 · sourcepub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
T: 'static + Error,
pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
T: 'static + Error,
Forwards to the method defined on the type dyn Error
.
sourceimpl dyn Error + Send + Sync + 'static
impl dyn Error + Send + Sync + 'static
1.3.0 · sourcepub fn is<T>(&self) -> bool where
T: 'static + Error,
pub fn is<T>(&self) -> bool where
T: 'static + Error,
Forwards to the method defined on the type dyn Error
.
1.3.0 · sourcepub fn downcast_ref<T>(&self) -> Option<&T> where
T: 'static + Error,
pub fn downcast_ref<T>(&self) -> Option<&T> where
T: 'static + Error,
Forwards to the method defined on the type dyn Error
.
1.3.0 · sourcepub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
T: 'static + Error,
pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
T: 'static + Error,
Forwards to the method defined on the type dyn Error
.
sourceimpl dyn Error + 'static
impl dyn Error + 'static
1.3.0 · sourcepub fn downcast<T>(
self: Box<dyn Error + 'static, Global>
) -> Result<Box<T, Global>, Box<dyn Error + 'static, Global>> where
T: 'static + Error,
pub fn downcast<T>(
self: Box<dyn Error + 'static, Global>
) -> Result<Box<T, Global>, Box<dyn Error + 'static, Global>> where
T: 'static + Error,
Attempts to downcast the box to a concrete type.
sourcepub fn chain(&self) -> Chain<'_>ⓘNotable traits for Chain<'a>impl<'a> Iterator for Chain<'a> type Item = &'a (dyn Error + 'static);
🔬 This is a nightly-only experimental API. (error_iter
)
pub fn chain(&self) -> Chain<'_>ⓘNotable traits for Chain<'a>impl<'a> Iterator for Chain<'a> type Item = &'a (dyn Error + 'static);
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());
Trait Implementations
Implementors
impl Error for std_tools::dependencies::derive_tools::dependencies::parse_display::helpers::regex::Error
impl Error for std_tools::dependencies::strs_tools::string::number::Error
impl Error for Infallible
impl Error for VarError
impl Error for RecvTimeoutError
impl Error for TryRecvError
impl Error for time::ParseError
impl Error for RoundingError
impl Error for !
impl Error for std_tools::dependencies::derive_tools::dependencies::parse_display::ParseError
impl Error for TryReserveError
impl Error for FromVecWithNulError
impl Error for IntoStringError
impl Error for NulError
impl Error for FromUtf8Error
impl Error for FromUtf16Error
impl Error for LayoutError
impl Error for AllocError
impl Error for TryFromSliceError
impl Error for BorrowError
impl Error for BorrowMutError
impl Error for CharTryFromError
impl Error for ParseCharError
impl Error for DecodeUtf16Error
impl Error for TryFromCharError
impl Error for FromBytesUntilNulError
impl Error for FromBytesWithNulError
impl Error for ParseFloatError
impl Error for ParseIntError
impl Error for TryFromIntError
impl Error for ParseBoolError
impl Error for Utf8Error
impl Error for FromFloatSecsError
impl Error for JoinPathsError
impl Error for WriterPanicked
impl Error for std::io::error::Error
impl Error for AddrParseError
impl Error for StripPrefixError
impl Error for ExitStatusError
impl Error for RecvError
impl Error for AccessError
impl Error for SystemTimeError
impl Error for OutOfRangeError
impl Error for chrono::format::ParseError
impl Error for std_tools::protected::dt::protected::fmt::Error
impl Error for BasicError
impl Error for CaseFoldError
impl Error for Error
impl Error for Error
impl Error for Error
impl Error for Error
impl Error for UnicodeWordError
impl<'a, K, V> Error for alloc::collections::btree::map::entry::OccupiedError<'a, K, V, Global> where
K: Debug + Ord,
V: Debug,
impl<'a, K, V> Error for std::collections::hash::map::OccupiedError<'a, K, V> where
K: Debug,
V: Debug,
impl<'a, T> Error for &'a T where
T: Error + ?Sized,
impl<I> Error for ExactlyOneError<I> where
I: Iterator + Debug,
<I as Iterator>::Item: Debug,
impl<L, R> Error for Either<L, R> where
L: Error,
R: Error,
Either
implements Error
if both L
and R
implement it.