examples: More robust cli arg handling

examples/src/bin/decodebin.rs

@@ -12,7 +12,8 @@ fn main() {
     let uri: &str = if args.len() == 2 {
         args[1].as_ref()
     } else {
-        panic!("Usage: decodebin file_path")
+        println!("Usage: decodebin file_path");
+        std::process::exit(-1);
     };
 
     let pipeline = gst::Pipeline::new(None);

examples/src/bin/playbin.rs

@@ -12,7 +12,8 @@ fn main() {
     let uri: &str = if args.len() == 2 {
         args[1].as_ref()
     } else {
-        panic!("Usage: playbin uri")
+        println!("Usage: playbin uri");
+        std::process::exit(-1);
     };
 
     let playbin = gst::ElementFactory::make("playbin", None).unwrap();

examples/src/bin/player.rs

@@ -70,7 +70,8 @@ fn main() {
     let uri: &str = if args.len() == 2 {
         args[1].as_ref()
     } else {
-        panic!("Usage: player uri")
+        println!("Usage: player uri");
+        std::process::exit(-1);
     };
 
     #[cfg(not(feature = "gst-player"))] {

examples/src/bin/toc.rs

@@ -12,7 +12,8 @@ fn main() {
     let uri: &str = if args.len() == 2 {
         args[1].as_ref()
     } else {
-        panic!("Usage: toc file_path")
+        println!("Usage: toc file_path");
+        std::process::exit(-1);
     };
 
     let pipeline = gst::Pipeline::new(None);