impl Error

fn from_args<'a>(message: Arguments<'a>) -> Error

Creates a new error value from core::fmt::Arguments.

It is expected to use format_args! from Rust's standard library (available in core) to create a core::fmt::Arguments.

Callers should generally use their own error types. But in some circumstances, it can be convenient to manufacture a Jiff error value specifically.

Core-only environments

In core-only environments without a dynamic memory allocator, error messages may be degraded in some cases. For example, if the given core::fmt::Arguments could not be converted to a simple borrowed &str, then this will ignore the input given and return an "unknown" Jiff error.

Example

use jiff::Error;

let err = Error::from_args(format_args!("something failed"));
assert_eq!(err.to_string(), "something failed");

fn is_range(&self) -> bool

Returns true when this error originated as a result of a value being out of Jiff's supported range.

Example

use jiff::civil::Date;

assert!(Date::new(2025, 2, 29).unwrap_err().is_range());
assert!("2025-02-29".parse::<Date>().unwrap_err().is_range());
assert!(Date::strptime("%Y-%m-%d", "2025-02-29").unwrap_err().is_range());

fn is_invalid_parameter(&self) -> bool

Returns true when this error originated as a result of an invalid configuration of parameters to a function call.

This particular error category is somewhat nebulous, but it's generally meant to cover errors that could have been statically prevented by Jiff with more types in its API. Instead, a smaller API is preferred.

Example: invalid rounding options

use jiff::{SpanRound, ToSpan, Unit};

let span = 44.seconds();
let err = span.round(
    SpanRound::new().smallest(Unit::Second).increment(45),
).unwrap_err();
// Rounding increments for seconds must divide evenly into `60`.
// But `45` does not. Thus, this is a "configuration" error.
assert!(err.is_invalid_parameter());

Example: invalid units

One cannot round a span between dates to units less than days:

use jiff::{civil::date, Unit};

let date1 = date(2025, 3, 18);
let date2 = date(2025, 12, 21);
let err = date1.until((Unit::Hour, date2)).unwrap_err();
assert!(err.is_invalid_parameter());

Similarly, one cannot round a span between times to units greater than hours:

use jiff::{civil::time, Unit};

let time1 = time(9, 39, 0, 0);
let time2 = time(17, 0, 0, 0);
let err = time1.until((Unit::Day, time2)).unwrap_err();
assert!(err.is_invalid_parameter());

fn is_crate_feature(&self) -> bool

Returns true when this error originated as a result of an operation failing because an appropriate Jiff crate feature was not enabled.

Example

use jiff::tz::TimeZone;

// This passes when the `tz-system` crate feature is NOT enabled.
assert!(TimeZone::try_system().unwrap_err().is_crate_feature());