# facet-error

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# facet-error

A `thiserror` replacement powered by facet reflection. This crate is a plugin for `#[derive(Facet)]` that generates `Display` and `Error` trait implementations from doc comments.

## Usage

```rust
use facet::Facet;

#[derive(Facet, Debug)]
#[facet(derive(Error))]
#[repr(u8)]
pub enum MyError {
    /// something went wrong
    Unknown,

    /// invalid value: {0}
    InvalidValue(String),

    /// invalid header (expected {expected}, found {found})
    InvalidHeader { expected: String, found: String },
}
```

This generates:
- `impl Display for MyError` using doc comments as format strings
- `impl Error for MyError` with proper `source()` implementation
- Field interpolation works automatically for struct variants (e.g., `{expected}`, `{found}`)
- Tuple variants support positional interpolation (e.g., `{0}`)

## Features

- **Doc-driven Display**: Doc comments become your error messages
- **Field interpolation**: Reference struct fields by name in messages
- **Zero boilerplate**: No manual Display or Error implementations
- **Integration with facet**: Works seamlessly with the facet reflection system

## Future Work

- `#[facet(error::source)]` - mark fields as error sources
- `#[facet(error::from)]` - generate `From` implementations
- Support for error wrapping and transparent delegation

## Sponsors

Thanks to all individual sponsors:

<p> <a href="https://github.com/sponsors/fasterthanlime">
<picture>
<source media="(prefers-color-scheme: dark)" srcset="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/github-dark.svg">
<img src="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/github-light.svg" height="40" alt="GitHub Sponsors">
</picture>
</a> <a href="https://patreon.com/fasterthanlime">
    <picture>
    <source media="(prefers-color-scheme: dark)" srcset="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/patreon-dark.svg">
    <img src="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/patreon-light.svg" height="40" alt="Patreon">
    </picture>
</a> </p>

...along with corporate sponsors:

<p> <a href="https://aws.amazon.com">
<picture>
<source media="(prefers-color-scheme: dark)" srcset="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/aws-dark.svg">
<img src="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/aws-light.svg" height="40" alt="AWS">
</picture>
</a> <a href="https://zed.dev">
<picture>
<source media="(prefers-color-scheme: dark)" srcset="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/zed-dark.svg">
<img src="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/zed-light.svg" height="40" alt="Zed">
</picture>
</a> <a href="https://depot.dev?utm_source=facet">
<picture>
<source media="(prefers-color-scheme: dark)" srcset="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/depot-dark.svg">
<img src="https://github.com/facet-rs/facet/raw/main/static/sponsors-v3/depot-light.svg" height="40" alt="Depot">
</picture>
</a> </p>

...without whom this work could not exist.

## Special thanks

The facet logo was drawn by [Misiasart](https://misiasart.com/).

## License

Licensed under either of:

- Apache License, Version 2.0 ([LICENSE-APACHE](https://github.com/facet-rs/facet/blob/main/LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
- MIT license ([LICENSE-MIT](https://github.com/facet-rs/facet/blob/main/LICENSE-MIT) or <http://opensource.org/licenses/MIT>)

at your option.
