enhance commandline parsing

* prefere settings in Cargo.toml
* introduce option dbdriver

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

src/main.rs

@@ -14,8 +14,31 @@ fn main() {
     println!("{}", &res);
 
     let yaml = load_yaml!("cli.yml");
-    let _matches = App::from_yaml(yaml).get_matches();
+    let matches = App::from_yaml(yaml)
+        .name(crate_name!())
+        .version(crate_version!())
+        .author(crate_authors!())
+        .about(crate_description!())
+        .get_matches();
 
+    // Gets a options value if supplied by user. otherwise set defaults
+    let config = matches.value_of("config").unwrap_or("default.conf");
+    println!("Value for config: {}", config);
+
+    let dbdriver = matches.value_of("dbdriver").unwrap_or("sqlite3");
+    println!("Value for database driver: {}", dbdriver);
+
+    // Vary the output based on how many times the user used the "verbose" flag
+    // (i.e. ' -v -v -v' or 'myprog -vvv' vs 'myprog -v'
+    match matches.occurrences_of("v") {
+        0 => println!("No verbose info"),
+        1 => println!("Some verbose info"),
+        2 => println!("Tons of verbose info"),
+        3 | _ => println!("Don't be crazy"),
+    }
+
+
+    // Starting the program logic
     let res = t!("main.start", lang);
     println!("{}", &res);
 }