pub enum Error {
    Leaf {
        user_id: i32,
    },
    Intermediate {
        source: Error,
    },
}
Expand description

An enumeration of possible errors.

This will create a number of context selectors:

Leaf errors

Context selectors for error variants without a source, such as LeafSnafu, have methods to construct them, such as LeafSnafu::build or LeafSnafu::fail. The ensure macro also accepts these kinds of context selectors.

use snafu::prelude::*;

fn always_fails() -> Result<(), Error> {
    LeafSnafu { user_id: 42 }.fail()
}

fn sometimes_fails(user_id: i32) -> Result<(), Error> {
    ensure!(user_id > 0, LeafSnafu { user_id });
    Ok(())
}

Intermediate errors

Context selectors for error variants with a source, such as IntermediateSnafu, are intended to be used with the ResultExt::context family of methods.

use snafu::prelude::*;

fn load_config_file() -> Result<usize, Error> {
    let config = std::fs::read_to_string("/path/to/my/config/file").context(IntermediateSnafu)?;
    Ok(config.len())
}

Variants

Leaf

Fields

user_id: i32

Intermediate

Fields

source: Error

Trait Implementations

Formats the value using the given formatter. Read more

Formats the value using the given formatter. Read more

👎Deprecated since 1.42.0:

use the Display impl or to_string()

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

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

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

Provides type based access to context intended for error reports. Read more

Returns a Backtrace that may be printed.

Returns an iterator for traversing the chain of errors, starting with the current error and continuing with recursive calls to Error::source. Read more

The underlying error

Combine the information to produce the error

The underlying error

Combine the information to produce the error

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

For maximum effectiveness, this needs to be called as a method to benefit from Rust’s automatic dereferencing of method receivers. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

🔬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

Converts the given value to a String. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.