README.md

slog-unwrap

This crate provides .unwrap_or_log() and .expect_or_log() methods on Result and Option types that log failed unwraps to a slog::Logger. This is useful when, for example, you have a syslog drain or a database drain, and you want your unwrap failures to show up there instead of being printed to stderr.

Its API aims to mirror Rust's std — see all the supported methods below. Failed unwraps are logged at a level of Critical.

Usage

Add the following to your Cargo.toml:

slog-unwrap = "0.9"

Next, bring the ResultExt and/or OptionExt traits into scope, and make use of the new logging methods.

use slog_unwrap::ResultExt;

let logger = slog::Logger::root(slog::Discard, slog::o!());
let not_great: Result<(), _> = Result::Err("not terrible");

// Logs the failed unwrap to `logger` and panics
not_great.unwrap_or_log(&logger);

Methods

std method	slog-unwrap form	trait
Result::unwrap()	Result::unwrap_or_log(&log)	ResultExt
Result::expect(msg)	Result::expect_or_log(&log, msg)	ResultExt
Result::unwrap_err()	Result::unwrap_err_or_log(&log)	ResultExt
Result::expect_err(msg)	Result::expect_err_or_log(&log, msg)	ResultExt
Option::unwrap()	Option::unwrap_or_log(&log)	OptionExt
Option::expect(msg)	Option::expect_or_log(&log, msg)	OptionExt
Option::unwrap_none()†	Option::unwrap_none_or_log(&log)	OptionExt
Option::expect_none(msg)†	Option::expect_none_or_log(&log, msg)	OptionExt

†: unstable in std
Note: enabling the scope feature drops the &log argument from all methods.

Features

• panic-quiet: causes failed unwraps to panic with an empty message.
  This feature is enabled by default — if you'd like the unwrap error message to also show in the panic message, disable default features in your Cargo.toml as follows:
  slog-unwrap = { version = "0.9", default-features = false }
• scope: adds support for slog-scope, which removes the need to pass a slog::Logger to the various methods.

Alternatives

See slog-unwraps, another crate with a similar featureset.