| use std::error::Error; |
| use std::io; |
| use std::process; |
| |
| fn run() -> Result<(), Box<dyn Error>> { |
| let mut wtr = csv::Writer::from_writer(io::stdout()); |
| |
| // We still need to write headers manually. |
| wtr.write_record(&[ |
| "City", |
| "State", |
| "Population", |
| "Latitude", |
| "Longitude", |
| ])?; |
| |
| // But now we can write records by providing a normal Rust value. |
| // |
| // Note that the odd `None::<u64>` syntax is required because `None` on |
| // its own doesn't have a concrete type, but Serde needs a concrete type |
| // in order to serialize it. That is, `None` has type `Option<T>` but |
| // `None::<u64>` has type `Option<u64>`. |
| wtr.serialize(( |
| "Davidsons Landing", |
| "AK", |
| None::<u64>, |
| 65.2419444, |
| -165.2716667, |
| ))?; |
| wtr.serialize(("Kenai", "AK", Some(7610), 60.5544444, -151.2583333))?; |
| wtr.serialize(("Oakman", "AL", None::<u64>, 33.7133333, -87.3886111))?; |
| |
| wtr.flush()?; |
| Ok(()) |
| } |
| |
| fn main() { |
| if let Err(err) = run() { |
| println!("{}", err); |
| process::exit(1); |
| } |
| } |