file_with_context.rs

fn render_docs(source: &Path, dest: &Path) -> Result<(), io::Error> {
  let dir_list = try!(read_dir(source).context(source));
  for entry_res in dir_list {
    let entry = try!(entry_res.context(source));
    let path = entry.path();
    let file = try!(File::open(&path).context(&path));
    for line_res in file.lines() {
      let line = try!(line_res.context(&path));
      // ...