Added dry-run global argument

src/command/dedupe.rs

@@ -15,13 +15,16 @@ pub fn get_command<'a>() -> Command<'a, str>{
             )
         })
         .runner(| _args, matches| {
-            // println!("Running dedupe, logging = {}", args);
+            let dry_run = matches.is_present("dry-run");
             match matches.values_of("playlist") {
                 Some(playlists) => {
                     for path in playlists {
                         let playlist = Playlist::read(path)?;
-                        println!("{:?}", playlist);
-                        playlist.write(path)?
+                        if ! dry_run {
+                            playlist.write(path)?
+                        } else {
+                            println!("{:?}", playlist);
+                        }
                     }
                     Ok(())
                 },

src/main.rs

@@ -22,6 +22,13 @@ fn main() {
                     .value_name("VERBOSITY")
                     .help("Sets the logging verbosity, defaults to \"INFO\""),
             )
+            .arg(
+                Arg::with_name("dry-run")
+                    .long("dry-run")
+                    .global(true)
+                    .takes_value(false)
+                    .help("Make no changes and print expected output")
+            )
         })
         .args(|_args, matches| matches.value_of("verbose").unwrap_or("INFO"))
         .add_cmd(command::dedupe::get_command())