Struct snafu::Location

#[non_exhaustive]
pub struct Location {
    pub file: &'static str,
    pub line: u32,
    pub column: u32,
}

The source code location where the error was reported.

To use it, add a field of type Location to your error and register it as implicitly generated data. When constructing the error, you do not need to provide the location:

#[derive(Debug, Snafu)]
struct NeighborhoodError {
    #[snafu(implicit)]
    loc: snafu::Location,
}

fn check_next_door() -> Result<(), NeighborhoodError> {
    ensure!(everything_quiet(), NeighborhoodSnafu);
    Ok(())
}

Limitations

Disabled context selectors

If you have disabled the context selector, SNAFU will not be able to capture an accurate location.

As a workaround, re-enable the context selector.

Asynchronous code

When using SNAFU’s TryFutureExt or TryStreamExt extension traits, the automatically captured location will correspond to where the future or stream was polled, not where it was created. Additionally, many Future or Stream combinators do not forward the caller’s location to their closures, causing the recorded location to be inside of the future combinator’s library.

There are two workarounds:

1. Use the location! macro
2. Use ResultExt instead

// Non-ideal: will report where `wrapped_error_future` is `.await`ed.
let wrapped_error_future = error_future.context(ImplicitLocationSnafu);

// Better: will report the location of `.context`.
let wrapped_error_future = async { error_future.await.context(ImplicitLocationSnafu) };

// Better: Will report the location of `location!`
let wrapped_error_future = error_future.with_context(|_| ExplicitLocationSnafu {
    location: location!(),
});

#[derive(Debug, Snafu)]
struct ImplicitLocationError {
    source: AnotherError,
    #[snafu(implicit)]
    location: Location,
}

#[derive(Debug, Snafu)]
struct ExplicitLocationError {
    source: AnotherError,
    location: Location,
}

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

file: &'static str

The file where the error was reported

line: u32

The line where the error was reported

column: u32

The column where the error was reported

Implementations

impl Location

pub fn new(file: &'static str, line: u32, column: u32) -> Self

Constructs a Location using the given information

Trait Implementations

impl Clone for Location

fn clone(&self) -> Location

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Location

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

Formats the value using the given formatter.

impl Default for Location

fn default() -> Self

Returns the “default value” for a type.

impl Display for Location

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

Formats the value using the given formatter.

impl GenerateImplicitData for Location

fn generate() -> Self

Build the data.

fn generate_with_source(source: &dyn Error) -> Self

where Self: Sized,

Build the data using the given source

impl Copy for Location