From 09b25cb803adf5ac51a4a73bea241e6b761edcac Mon Sep 17 00:00:00 2001
From: Leo Horie <leohorie@hotmail.com>
Date: Wed, 10 Dec 2014 22:34:20 -0500
Subject: [PATCH 1/2] #378 fix strategy none semantics

---
 docs/mithril.redraw.md | 10 +++++++++-
 mithril.js             | 13 ++++++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/docs/mithril.redraw.md b/docs/mithril.redraw.md
index 16c8f504..344620b4 100644
--- a/docs/mithril.redraw.md
+++ b/docs/mithril.redraw.md
@@ -122,7 +122,7 @@ Note that the redraw strategy is a global setting that affects the entire templa
 
 ### Preventing redraws on events
 
-Sometimes you only care about a particular condition in an event and want to ignore it if this condition is not met. 
+Sometimes you only care about a particular condition in an event and want the event to not trigger a redraw if this condition is not met. 
 For example, you might only be interested in running a redraw if a user presses the space bar, and you might not want to waste a redraw if the user presses any other key. In that case, it's possible to skip redrawing altogether by calling `m.redraw.strategy("none")`
 
 ```javascript
@@ -132,6 +132,14 @@ m("input", {onkeydown: function(e) {
 }})
 ```
 
+There are some important semantic caveats for `m.redraw.strategy("none")` that you should be aware of: Setting the strategy to `"none"` only affects **synchronous** redraws. As soon as the event handler returns, the strategy is set back to "diff".
+
+If you set strategy to `"none"` but then proceed to trigger a redraw asynchronously, either via `start/endComputation`, `m.redraw` or `m.request`, a redraw *will* occur, using the `"diff"` strategy.
+
+Additionally, calling `m.redraw` synchronously after calling `m.redraw.strategy("none")` resets the strategy to `"diff"`.
+
+Lastly, be aware that if a user action triggers more than one event handler (for example, oninput and onkeypress, or an event bubbling up to event handlers in multiple ancestor elements), every event triggers a redraw by default. Setting strategy to none in any one of those handlers will not affect the redrawing strategy of other handlers (and remember that `strategy("none")` has no effect on asynchronous redraws).
+
 ---
 
 ### Forcing redraw
diff --git a/mithril.js b/mithril.js
index ff799287..db6d7d5c 100644
--- a/mithril.js
+++ b/mithril.js
@@ -409,7 +409,7 @@ var m = (function app(window, undefined) {
 			m.startComputation();
 			try {return callback.call(object, e)}
 			finally {
-				m.endComputation()
+				endFirstComputation()
 			}
 		}
 	}
@@ -499,7 +499,7 @@ var m = (function app(window, undefined) {
 				controllers[index] = controller;
 				modules[index] = module
 			}
-			m.endComputation();
+			endFirstComputation();
 			return controllers[index]
 		}
 	};
@@ -523,7 +523,7 @@ var m = (function app(window, undefined) {
 	function redraw() {
 		var mode = m.redraw.strategy();
 		for (var i = 0, root; root = roots[i]; i++) {
-			if (controllers[i] && mode != "none") {
+			if (controllers[i]) {
 				m.render(root, modules[i].view(controllers[i]), mode === "all")
 			}
 		}
@@ -543,6 +543,13 @@ var m = (function app(window, undefined) {
 		pendingRequests = Math.max(pendingRequests - 1, 0);
 		if (pendingRequests === 0) m.redraw()
 	};
+	var endFirstComputation = function() {
+		if (m.redraw.strategy() == "none") {
+			pendingRequests--
+			m.redraw.strategy("diff")
+		}
+		else m.endComputation();
+	}
 
 	m.withAttr = function(prop, withAttrCallback) {
 		return function(e) {

From 3073b27abd82ab0b50e87c14c5362b8bafe97044 Mon Sep 17 00:00:00 2001
From: Leo Horie <leohorie@hotmail.com>
Date: Wed, 10 Dec 2014 23:06:15 -0500
Subject: [PATCH 2/2] improve loop

---
 mithril.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mithril.js b/mithril.js
index db6d7d5c..867d4ed7 100644
--- a/mithril.js
+++ b/mithril.js
@@ -521,10 +521,10 @@ var m = (function app(window, undefined) {
 	};
 	m.redraw.strategy = m.prop();
 	function redraw() {
-		var mode = m.redraw.strategy();
+		var forceRedraw = m.redraw.strategy() === "all";
 		for (var i = 0, root; root = roots[i]; i++) {
 			if (controllers[i]) {
-				m.render(root, modules[i].view(controllers[i]), mode === "all")
+				m.render(root, modules[i].view(controllers[i]), forceRedraw)
 			}
 		}
 		//after rendering within a routed context, we need to scroll back to the top, and fetch the document title for history.pushState