This crate provides .unwrap_or_log() and .expect_or_log() methods on Result and Option types that log failed unwraps to a [tracing::Subscriber]. This is useful when, for example, you are logging to syslog or a database, 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 [ERROR].
Add the following to your Cargo.toml:
toml
tracing-unwrap = "0.10"
Next, bring the [ResultExt] and/or [OptionExt] traits into scope, and make use of the new logging methods.
```rust
use tracing_unwrap::ResultExt;
tracingsubscriber::fmt().init(); let notgreat: Result<(), _> = Result::Err("not terrible");
// Logs the failed unwrap and panics notgreat.unwrapor_log(); ```
| std method | tracing-unwrap form | trait |
|--------------------------------| ----------------------------------------|---------------|
| [Result::unwrap()] | [Result::unwrap_or_log()] | [ResultExt] |
| [Result::expect(msg)] | [Result::expect_or_log(msg)] | [ResultExt] |
| [Result::unwrap_err()] | [Result::unwrap_err_or_log()] | [ResultExt] |
| [Result::expect_err(msg)] | [Result::expect_err_or_log(msg)] | [ResultExt] |
| [Option::unwrap()] | [Option::unwrap_or_log()] | [OptionExt] |
| [Option::expect(msg)] | [Option::expect_or_log(msg)] | [OptionExt] |
| [Option::unwrap_none()]† | [Option::unwrap_none_or_log()] | [OptionExt] |
| [Option::expect_none(msg)]† | [Option::expect_none_or_log(msg)] | [OptionExt] |
†: no longer in std, see rust-lang/rust#62633
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:
tracing-unwrap = { version = "0.10", default-features = false }
log-location: calls [std::panic::Location::caller()] to determine the location of a failed unwrap.