backon-macros  

Attribute macros that make backon retry APIs feel like native syntax.

• Fluent ergonomics: Mark a function with #[backon] and reuse the builder-style retry API without writing closures.
• Async & sync aware: The macro inspects your signature to choose between Retryable and BlockingRetryable.
• Configurable: Opt into custom backoff strategies, sleepers, filters, notifications, or context capture with simple arguments.

Installation

Add both backon and backon-macros to your Cargo.toml:

[dependencies]
backon = "1"
backon-macros = "1"

Usage

Annotate any free function or inherent method (taking &self) with #[backon]. The macro rewrites the body so it runs inside a retry loop using the backon primitives.

use anyhow::Result;
use backon::TokioSleeper;
use backon_macros::backon;

#[backon(
    backoff = backon::ExponentialBuilder::default,
    sleep = TokioSleeper::sleep,
    when = |e: &anyhow::Error| e.to_string() == "temporary",
    notify = |err: &anyhow::Error, dur| tracing::warn!(?err, ?dur, "retrying")
)]
async fn fetch_data() -> Result<String> {
    Ok("value".to_string())
}

Parameters

Context mode

context = true is available for free functions and methods without receivers, and for methods that take ownership of their receiver. It cannot be combined with &self or &mut self methods; those cases must still use manual RetryableWithContext until dedicated support is added.

Examples

Try the ready-to-run programs under examples/ with cargo run --example ... for async, blocking, and method-based workflows. For more exhaustive coverage, check the trybuild tests.

Limitations

• Methods that take &mut self or own self are currently rejected with a compile-time error; write manual retry loops for now.
• The macro does not support arbitrary patterns in parameter position—each argument must bind to an identifier.
• The generated code depends on the backon crate at runtime; ensure both crates are included in your workspace.

License

Licensed under Apache License, Version 2.0.