# exitfailure - convenient newtype wrappers for using ? in main()
[](https://travis-ci.org/tismith/exitfailure)
[](https://ci.appveyor.com/project/tismith/exitfailure/branch/master)
[](https://codecov.io/gh/tismith/exitfailure)
[](https://crates.io/crates/exitfailure)
`exitfailure` provides some newtype wrappers to help with using ? in `main()`.
It is intended to be used with rust 1.26 and above's "? in main()" feature (see the [tracking issue here](https://github.com/rust-lang/rust/issues/43301)).
The primary items exported by this library are:
- `ExitFailure`: a wrapper around `failure::Error` to allow ? printing from main
to present a nicer error message, including any available context and backtrace.
- `ExitDisplay<E>`: a wrapper around `E: std::fmt::Display` to allow the error message
from main to use `Display` and not `Debug`.
For more information, including more details on the types, please see the [API Documentation](https://docs.rs/exitfailure/).
Example:
```rust
#[macro use] extern crate failure;
extern crate exitfailure;
use failure::ResultExt;
use exitfailure::ExitFailure;
fn main() -> Result<(), ExitFailure> {
Ok(some_fn()?)
}
fn some_fn() -> Result<(), failure::Error> {
let error = Err(failure::err_msg("root cause failure"));
Ok(error.context("this is some context".to_string())?)
}
```
This will print, when executed:
```ignore
Error: this is some context
Info: caused by root cause failure
```
If the environment variable RUST_BACKTRACE=1 is set, then the printing will
include whatever backtrace information is provided by the `failure::Error`
that is being wrapped.
## License
Licensed under either of
* Apache License, Version 2.0
([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license
([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
at your option.
## Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.