# HG changeset patch
# User Matt Johnston <matt@ucc.asn.au>
# Date 1482279373 -28800
# Node ID f2508125adf15ec4091f6d31ead8fcb8bfbe9b78
# Parent  038734052b2021e46e1be80ec609bb4408ccf215
Try using traits for periodic stream

diff -r 038734052b20 -r f2508125adf1 rust/src/main.rs
--- a/rust/src/main.rs	Fri Dec 16 01:10:57 2016 +0800
+++ b/rust/src/main.rs	Wed Dec 21 08:16:13 2016 +0800
@@ -4,13 +4,12 @@
 
 use std::time::Duration;
 use std::cell::RefCell;
+use std::io::{self, Read, Write};
 
 use tokio_core::reactor::Interval;
 use tokio_core::reactor::Core;
 use tokio_core::reactor::Handle;
-use futures::Stream;
-use futures::Future;
-use futures::IntoFuture;
+use futures::{Future, failed, Poll, Async, Stream};
 
 pub struct Reading {
     name: String,
@@ -23,6 +22,30 @@
     current: f32,
 }
 
+struct Periodic<T> {
+    interval: Interval,
+}
+
+trait Ticker {
+    type TickItem;
+    fn tick(&self) -> Self::TickItem;
+}
+
+impl<T: Ticker> Stream for Periodic<T> {
+    type Item = T::TickItem;
+    type Error = io::Error;
+
+    fn poll(&mut self) -> Poll<Option<Self::Item>, io::Error> {
+        self.interval.poll().map(|a| {
+            if let Async::Ready(t) = a {
+                Async::Ready(self.tick())
+            } else {
+                a
+            }
+        })
+    }
+}
+
 impl Sensor {
 
     fn step(&mut self) -> Readings {
@@ -36,7 +59,7 @@
         Sensor { current: 22.0 }
     }
 
-    pub fn run(handle: &Handle) -> impl Stream<Item=Readings> {
+    pub fn run(handle: &Handle) -> Box<Stream<Item=Readings, Error=io::Error>> {
         let mut s = Sensor::new();
 
         let dur = Duration::from_millis(400);