Attribute Macro context

#[context]

Use a doc comment to annotate the failure context of a function or try block.

Examples

use context_attribute::context;
use failure::{ensure, ResultExt};

fn main() -> Result<(), failure::Error> {
    let _ = square(2)?;
    let _ = square(5)?;
    let _ = square(11)?;
}

/// Square a number if it's less than 10.
#[context]
fn square(num: usize) -> Result<String, >{
    ensure!(num < 10, "Number was larger than 10");
    num * num
}