Better usage of clap.

2018/Cargo.toml

@@ -2,6 +2,7 @@
 name = "aoc-2018"
 version = "0.1.0"
 authors = ["Bert Peters <bert@bertptrs.nl>"]
+description = "Implementation of the problems of Advent of Code 2018"
 
 [dependencies]
 clap = "2.32"

2018/src/main.rs

@@ -1,5 +1,5 @@
 extern crate chrono;
-extern crate clap;
+#[macro_use] extern crate clap;
 extern crate aoc_2018;
 
 use std::fs;
@@ -8,27 +8,24 @@ use std::time::Instant;
 
 use aoc_2018::*;
 
-use clap::{App, Arg};
+use clap::Arg;
 
-fn get_impl(day: &str) -> Box<common::Solution> {
-    match day.parse() {
-        Ok(1) => Box::new(day01::Day01::new()),
-        Ok(2) => Box::new(day02::Day02::new()),
-        Ok(3) => Box::new(day03::Day03::new()),
-        Ok(4) => Box::new(day04::Day04::new()),
-        Ok(5) => Box::new(day05::Day05::new()),
-        Ok(6) => Box::new(day06::Day06::new()),
-        Ok(7) => Box::new(day07::Day07::new()),
-        Ok(8) => Box::new(day08::Day08::new()),
-        Ok(val) => panic!("Unimplemented day {}", val),
-        _ => panic!("Invalid number"),
+fn get_impl(day: u32) -> Box<common::Solution> {
+    match day {
+        1 => Box::new(day01::Day01::new()),
+        2 => Box::new(day02::Day02::new()),
+        3 => Box::new(day03::Day03::new()),
+        4 => Box::new(day04::Day04::new()),
+        5 => Box::new(day05::Day05::new()),
+        6 => Box::new(day06::Day06::new()),
+        7 => Box::new(day07::Day07::new()),
+        8 => Box::new(day08::Day08::new()),
+        val => panic!("Unimplemented day {}", val),
     }
 }
 
 fn main() {
-    let matches = App::new("Advent of Code")
-        .version("2018")
-        .author("Bert Peters <bert@bertptrs.nl>")
+    let matches = app_from_crate!()
         .arg(Arg::with_name("day")
             .value_name("DAY")
             .help("Number of the day to execute")
@@ -36,7 +33,7 @@ fn main() {
             .takes_value(true))
         .arg(Arg::with_name("part2")
             .short("2")
-            .help("Whether to run part 2")
+            .help("Run part 2 instead of part 1")
             .long("part2"))
         .arg(Arg::with_name("input")
             .short("i")
@@ -49,7 +46,7 @@ fn main() {
             .help("Print the time for the result"))
         .get_matches();
 
-    let mut implementation = get_impl(matches.value_of("day").unwrap());
+    let mut implementation = get_impl(value_t_or_exit!(matches, "day", u32));
     let mut data: Box<io::Read> = match matches.value_of("input") {
         Some(filename) => { Box::new(fs::File::open(filename).unwrap()) }
         None => { Box::new(io::stdin()) }
@@ -74,9 +71,9 @@ mod tests {
     #[test]
     fn test_get_impl() {
         // Verify that we can load all days
-        let last_implemented = 6;
+        let last_implemented = 8;
         for d in 1..=last_implemented {
-            get_impl(&format!("{}", d));
+            get_impl(d);
         }
     }
 }