ez-err

The goal of this crate is to add simple and easy-to-use error handling. The amount of boilerplate code required to get the full set of features should be minimal. Ez-err includes the stack trace information directly in the error type in case of Err (almost no overhead if Ok). The approach is especially useful for any case where the error propagation might be deferred (code storing Results in a Vec and only later checking whether they are Ok or not). It is also worth taking a look at eget and eget_mut for more advanced error messages which include more information about the error.

Use cases

This crate can be useful for general purpose error handling. However, it should be helpful in scenarios where no source code information should be contained in the resulting product for any reason. Only relying on ez-err for error handling will provide full power over the error output. Disabling stack trace collection should also remove any source code information from the binary that would have been generated with ez-err.

How to use / Example

To use ez-err, you need to add use ez_err::prelude::* to your source file. Once that is done, you can use the custom Result<T> type in your functions and then handle all errors by using xxx.loc(flc!())?. It is possible to use this same pattern when converting from any error type to EzError.

use ez_err::prelude::*;
use std::io::Write;
fn save_log_output(log: String) -> Result<()> {
    // Try to open the file or return an error with stack trace.
    let mut file = std::fs::File::open("...").loc(flc!())?;
    // Try to write to the file or return an error with stack trace.
    write!(&mut file, "{}", log).loc(flc!())?;
    // Everything went well without an error.
    Ok(())
}
fn quit(log: String) {
    // Print the error to the console if there is any.
    let _optional_return: Option<()> = save_log_output(log).handle();
}

How does it work?

xxx.loc(flc!())? is made up of 3 parts: the loc function, the flc! macro, and the standard ? operator. The flc! macro will first expand to a ConstLocation containing information about the source code location where the macro was invoked. This information is passed into the loc function, which will store the location ONLY if it is currently an Err to minimize the overhead. The standard ? operator will then perform the already existing logic for error propagation. This approach requires no special backtrace configuration and can produce clean stack traces. It should be very fast by compiling down to just an additional if statement in the Ok-case.

Why should I use ez-err?

The advantage of this crate over others is simplicity. Other error handling crates require manually adding error reasons, which can be helpful but can often be overkill. Here is an example to show the difference between this crate and a popular one (error-chain):

fn error_producer() -> Result<i32> { /* ... */ }
// Propagate an error using error-chain
fn use_error_chain() -> Result<i32> {
    /* ... */
    let value: i32 = error_producer().chain_err(|| "error when getting value")?;
    Ok(value + 1)
}
// Propagate an error using ez-err
fn use_ez_err() -> ez_err::Result<i32> {
    /* ... */
    let value: i32 = error_producer().info(flc!())?;
    Ok(value + 1)
}

Features

• log - enable compatibility with the log crate. The code will by default output to error!(...).
• no_stacktrace - disable any stacktrace collection. This might be useful in a scenario where leaking source information is problematic.

License

This project is licensed under the MIT license.

Contribution

Any contribution intentionally submitted for inclusion in the work by you, shall be licensed as MIT, without any additional terms or conditions.

Special Thanks

This project is part of tools developed for CrushDepth. Feel free to take a look at some of our projects:

• Crush Depth / Crush Depth Studios
• Code Orchestra