Add experimental --notify option

See #139

cli/Cargo.toml

@@ -23,6 +23,7 @@ path = "src/main.rs"
 log = "0.4.14"
 watchexec = { path = "../lib", version = "1.17.1" }
 color-eyre = "0.5.11"
+notify-rust = "4.5.2"
 
 [dependencies.clap]
 version = "2.33.3"

cli/src/args.rs

@@ -131,7 +131,11 @@ pub fn get_args() -> Result<CliHandler> {
         .arg(Arg::with_name("watch-when-idle")
                  .help("Deprecated alias for --on-busy-update=do-nothing, which will become the default in 2.0.")
                  .short("W")
-                 .long("watch-when-idle"));
+                 .long("watch-when-idle"))
+        .arg(Arg::with_name("notif")
+                 .help("Send a desktop notification when watchexec notices a change (experimental, behaviour may change)")
+                 .short("N")
+                 .long("notify"));
 
     let mut raw_args: Vec<OsString> = env::args_os().collect();
 
@@ -279,7 +283,7 @@ pub fn get_args() -> Result<CliHandler> {
         LevelFilter::Warn
     };
 
-    CliHandler::new(config, loglevel, false)
+    CliHandler::new(config, loglevel, args.is_present("notif"))
 }
 
 // until 2.0

cli/src/handler.rs

@@ -1,5 +1,6 @@
 use color_eyre::eyre;
-use log::LevelFilter;
+use log::{warn, LevelFilter};
+use notify_rust::Notification;
 use watchexec::{
     config::Config,
     error::Result,
@@ -31,7 +32,21 @@ impl Handler for CliHandler {
     fn on_manual(&self) -> Result<bool> {
         self.inner.on_manual()
     }
+
     fn on_update(&self, ops: &[PathOp]) -> Result<bool> {
-        self.inner.on_update(ops)
+        self.inner.on_update(ops).map(|o| {
+            if self.notify {
+                Notification::new()
+                    .summary("Watchexec observed a change")
+                    .body("Watchexec has seen a change, the command may have restarted.")
+                    .show()
+                    .map(drop)
+                    .unwrap_or_else(|err| {
+                        warn!("Failed to send desktop notification: {}", err);
+                    });
+            }
+
+            o
+        })
     }
 }