Struct snafu::Whatever

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pub struct Whatever { /* private fields */ }
Expand description

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.

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impl Whatever

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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.

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impl Debug for Whatever

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

Formats the value using the given formatter. Read more
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impl Display for Whatever

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

Formats the value using the given formatter. Read more
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impl Error for Whateverwhere Self: Debug + Display,

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fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()
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fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting
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fn source(&self) -> Option<&(dyn Error + 'static)>

The lower-level source of this error, if any. Read more
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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. Read more
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impl ErrorCompat for Whatever

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

Returns a Backtrace that may be printed.
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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. Read more
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impl FromString for Whatever

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type Source = Box<dyn Error, Global>

The underlying error
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fn without_source(message: String) -> Self

Create a brand new error from the given string
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fn with_source(error: Self::Source, message: String) -> Self

Wrap an existing error with the given string

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> AsErrorSource for Twhere T: Error + 'static,

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fn as_error_source(&self) -> &(dyn Error + 'static)

For maximum effectiveness, this needs to be called as a method to benefit from Rust’s automatic dereferencing of method receivers.
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<E> Provider for Ewhere E: Error + ?Sized,

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

🔬This is a nightly-only experimental API. (provide_any)
Data providers should implement this method to provide all values they are able to provide by using demand. Read more
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impl<T> ToString for Twhere T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.