doc(client): show spawning a client future, clarify lazy in client example

examples/client.rs

@@ -28,32 +28,38 @@ fn main() {
         return;
     }
 
-    rt::run(rt::lazy(move || {
-        let client = Client::new();
-
-        client
-            // Fetch the url...
-            .get(url)
-            // And then, if we get a response back...
-            .and_then(|res| {
-                println!("Response: {}", res.status());
-                println!("Headers: {:#?}", res.headers());
-
-                // The body is a stream, and for_each returns a new Future
-                // when the stream is finished, and calls the closure on
-                // each chunk of the body...
-                res.into_body().for_each(|chunk| {
-                    io::stdout().write_all(&chunk)
-                        .map_err(|e| panic!("example expects stdout is open, error={}", e))
-                })
-            })
-            // If all good, just tell the user...
-            .map(|_| {
-                println!("\n\nDone.");
-            })
-            // If there was an error, let the user know...
-            .map_err(|err| {
-                eprintln!("Error {}", err);
-            })
-    }));
+    // Run the runtime with the future trying to fetch and print this URL.
+    //
+    // Note that in more complicated use cases, the runtime should probably
+    // run on its own, and futures should just be spawned into it.
+    rt::run(fetch_url(url));
+}
+
+fn fetch_url(url: hyper::Uri) -> impl Future<Item=(), Error=()> {
+    let client = Client::new();
+
+    client
+        // Fetch the url...
+        .get(url)
+        // And then, if we get a response back...
+        .and_then(|res| {
+            println!("Response: {}", res.status());
+            println!("Headers: {:#?}", res.headers());
+
+            // The body is a stream, and for_each returns a new Future
+            // when the stream is finished, and calls the closure on
+            // each chunk of the body...
+            res.into_body().for_each(|chunk| {
+                io::stdout().write_all(&chunk)
+                    .map_err(|e| panic!("example expects stdout is open, error={}", e))
+            })
+        })
+        // If all good, just tell the user...
+        .map(|_| {
+            println!("\n\nDone.");
+        })
+        // If there was an error, let the user know...
+        .map_err(|err| {
+            eprintln!("Error {}", err);
+        })
 }