skel.rs

// rust main skeleton 
//
// references: 
// error_chain: https://brson.github.io/2016/11/30/starting-with-error-chain

#![recursion_limit = "1024"]
#[macro_use]
extern crate error_chain;
// Create the Error, ErrorKind, ResultExt, and Result types
// note: other modules `use errors::*;` to get access to everything
mod errors { error_chain! { } }

use errors::*;

fn main() {
    if let Err(ref e) = run() {
        println!("error: {}", e);

        for e in e.iter().skip(1) {
            println!("caused by: {}", e);
        }

        // note: run with `RUST_BACKTRACE=1` if no backtrace is available
        if let Some(backtrace) = e.backtrace() {
            println!("backtrace: {:?}", backtrace);
        }

        ::std::process::exit(1);
    }
}

// Most functions will return the `Result` type, imported from the
// `errors` module. It is a typedef of the standard `Result` type
// for which the error type is always our own `Error`.
fn run() -> Result<()> {
  
  // example 
    use std::fs::File;
    // This operation will fail
    File::open("contacts").chain_err(|| "unable to open contacts file")?;
    Ok(())
}