From 7da2bdb82a72dffc8c72c1becf6f62aae52d32ce Mon Sep 17 00:00:00 2001
From: Igor Minar <igor@angularjs.org>
Date: Sat, 21 Jan 2012 00:01:44 -0800
Subject: [PATCH] fix(scope): support watching functions

currently we run into infinite digest if a function is being
watched as an expression. This is because we generate bound
function wrapper when the watch is processed via parser.

I'm not too keen on the solution because it relies on the unbound
fn that is being exposed for other reasons, but I can't think
of a better way to deal with this right now
---
 src/Angular.js            | 39 +++++++++++++++++++++------------------
 test/service/scopeSpec.js | 16 ++++++++++++++++
 2 files changed, 37 insertions(+), 18 deletions(-)

diff --git a/src/Angular.js b/src/Angular.js
index 3f272ec29b20..17ede3aa5c23 100644
--- a/src/Angular.js
+++ b/src/Angular.js
@@ -655,28 +655,31 @@ function equals(o1, o2) {
   if (o1 === null || o2 === null) return false;
   if (o1 !== o1 && o2 !== o2) return true; // NaN === NaN
   var t1 = typeof o1, t2 = typeof o2, length, key, keySet;
-  if (t1 == t2 && t1 == 'object') {
-    if (isArray(o1)) {
-      if ((length = o1.length) == o2.length) {
-        for(key=0; key<length; key++) {
-          if (!equals(o1[key], o2[key])) return false;
+  if (t1 == t2) {
+    if (t1 == 'object') {
+      if (isArray(o1)) {
+        if ((length = o1.length) == o2.length) {
+          for(key=0; key<length; key++) {
+            if (!equals(o1[key], o2[key])) return false;
+          }
+          return true;
         }
-        return true;
-      }
-    } else {
-      if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2)) return false;
-      keySet = {};
-      for(key in o1) {
-        if (key.charAt(0) !== '$' && !isFunction(o1[key]) && !equals(o1[key], o2[key])) {
-          return false;
+      } else {
+        if (isScope(o1) || isScope(o2) || isWindow(o1) || isWindow(o2)) return false;
+        keySet = {};
+        for(key in o1) {
+          if (key.charAt(0) !== '$' && !isFunction(o1[key]) && !equals(o1[key], o2[key])) {
+            return false;
+          }
+          keySet[key] = true;
         }
-        keySet[key] = true;
-      }
-      for(key in o2) {
-        if (!keySet[key] && key.charAt(0) !== '$' && !isFunction(o2[key])) return false;
+        for(key in o2) {
+          if (!keySet[key] && key.charAt(0) !== '$' && !isFunction(o2[key])) return false;
+        }
+        return true;
       }
-      return true;
     }
+    if (t1 == 'function' && o1.$unboundFn) return o1.$unboundFn === o2.$unboundFn;
   }
   return false;
 }
diff --git a/test/service/scopeSpec.js b/test/service/scopeSpec.js
index 308056847a9a..b1b870f41ad6 100644
--- a/test/service/scopeSpec.js
+++ b/test/service/scopeSpec.js
@@ -248,6 +248,22 @@ describe('Scope', function() {
     }));
 
 
+    it('should watch functions', function() {
+      module(provideLog);
+      inject(function($rootScope, log) {
+        $rootScope.fn = function() {return 'a'};
+        $rootScope.$watch('fn', function(scope, fn) {
+          log(fn());
+        });
+        $rootScope.$digest();
+        expect(log).toEqual('a');
+        $rootScope.fn = function() {return 'b'};
+        $rootScope.$digest();
+        expect(log).toEqual('a; b');
+      })
+    });
+
+
     it('should prevent $digest recursion', inject(function($rootScope) {
       var callCount = 0;
       $rootScope.$watch('name', function() {