port connections; DevicePorts -> PortList

src/device/chain.rs

@@ -27,6 +27,23 @@ impl Chain {
     }
 }
 
+impl PortList for Chain {
+    fn midi_ins (&self) -> Usually<Vec<String>> {
+        if let Some(device) = self.items.get(0) {
+            device.midi_ins()
+        } else {
+            Ok(vec![])
+        }
+    }
+    fn audio_outs (&self) -> Usually<Vec<String>> {
+        if let Some(device) = self.items.get(self.items.len().saturating_sub(1)) {
+            device.audio_outs()
+        } else {
+            Ok(vec![])
+        }
+    }
+}
+
 pub fn process (_: &mut Chain, _: &Client, _: &ProcessScope) -> Control {
     Control::Continue
 }
@@ -238,5 +255,3 @@ pub fn handle (state: &mut Chain, event: &AppEvent) -> Usually<bool> {
             |s: &mut Chain|s.handle_focus(&FocusEvent::Outward)]
     }))
 }
-
-impl DevicePorts for Chain {}