Struct failure::Error [−][src]
pub struct Error { /* fields omitted */ }The Error type, which can contain any failure.
Functions which accumulate many kinds of errors should return this type.
All failures can be converted into it, so functions which catch those
errors can be tried with ? inside of a function that returns this kind
of error.
In addition to implementing Debug and Display, this type carries Backtrace
information, and can be downcast into the failure that underlies it for
more detailed inspection.
Implementations
impl Error[src]
impl Error[src]pub fn from_boxed_compat(
err: Box<dyn StdError + Sync + Send + 'static>
) -> Error[src]
err: Box<dyn StdError + Sync + Send + 'static>
) -> Error
Creates an Error from Box<std::error::Error>.
This method is useful for comparability with code,
which does not use the Fail trait.
Example
use std::error::Error as StdError; use failure::Error; fn app_fn() -> Result<i32, Error> { let x = library_fn().map_err(Error::from_boxed_compat)?; Ok(x * 2) } fn library_fn() -> Result<i32, Box<StdError + Sync + Send + 'static>> { Ok(92) }
pub fn as_fail(&self) -> &dyn Fail[src]
Return a reference to the underlying failure that this Error
contains.
pub fn name(&self) -> Option<&str>[src]
Returns the name of the underlying fail.
pub fn cause(&self) -> &dyn Fail[src]
please use ‘as_fail()’ method instead
Returns a reference to the underlying cause of this Error. Unlike the
method on Fail, this does not return an Option. The Error type
always has an underlying failure.
This method has been deprecated in favor of the Error::as_fail method, which does the same thing.
pub fn backtrace(&self) -> &Backtrace[src]
Gets a reference to the Backtrace for this Error.
If the failure this wrapped carried a backtrace, that backtrace will
be returned. Otherwise, the backtrace will have been constructed at
the point that failure was cast into the Error type.
pub fn context<D: Display + Send + Sync + 'static>(
self,
context: D
) -> Context<D>[src]
self,
context: D
) -> Context<D>
Provides context for this Error.
This can provide additional information about this error, appropriate to the semantics of the current layer. That is, if you have a lower-level error, such as an IO error, you can provide additional context about what that error means in the context of your function. This gives users of this function more information about what has gone wrong.
This takes any type that implements Display, as well as
Send/Sync/'static. In practice, this means it can take a String
or a string literal, or a failure, or some other custom context-carrying
type.
pub fn compat(self) -> Compat<Error>[src]
Wraps Error in a compatibility type.
This type implements the Error trait from std::error. If you need
to pass failure’s Error to an interface that takes any Error, you
can use this method to get a compatible type.
pub fn downcast<T: Fail>(self) -> Result<T, Error>[src]
Attempts to downcast this Error to a particular Fail type.
This downcasts by value, returning an owned T if the underlying
failure is of the type T. For this reason it returns a Result - in
the case that the underlying error is of a different type, the
original Error is returned.
pub fn find_root_cause(&self) -> &dyn Fail[src]
Returns the “root cause” of this error - the last value in the
cause chain which does not return an underlying cause.
pub fn iter_causes(&self) -> Causes<'_>ⓘ[src]
Returns a iterator over the causes of this error with the cause
of the fail as the first item and the root_cause as the final item.
Use iter_chain to also include the fail of this error itself.
pub fn iter_chain(&self) -> Causes<'_>ⓘ[src]
Returns a iterator over all fails up the chain from the current
as the first item up to the root_cause as the final item.
This means that the chain also includes the fail itself which
means that it does not start with cause. To skip the outermost
fail use iter_causes instead.
pub fn downcast_ref<T: Fail>(&self) -> Option<&T>[src]
Attempts to downcast this Error to a particular Fail type by
reference.
If the underlying error is not of type T, this will return None.
pub fn downcast_mut<T: Fail>(&mut self) -> Option<&mut T>[src]
Attempts to downcast this Error to a particular Fail type by
mutable reference.
If the underlying error is not of type T, this will return None.
pub fn root_cause(&self) -> &dyn Fail[src]
please use the ‘find_root_cause()’ method instead
Deprecated alias to find_root_cause.
pub fn causes(&self) -> Causes<'_>ⓘ[src]
please use the ‘iter_chain()’ method instead
Deprecated alias to iter_causes.