base::Bind: Implement CancelableCallback to replace CancelableTaske.

base/cancelable_callback_unittest.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/cancelable_callback.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace {
+
+class HelperObject {
+ public:
+  HelperObject() : number_(0) { }
+  void IncrementNumber() { number_++; }
+  void IncrementNumberBy(int n) { number_ += n; }
+  int number() const { return number_; }
+
+ private:
+  int number_;
+};
+
+TEST(CancelableCallbackTest, Cancel) {
+  HelperObject obj;
+  CancelableCallback cancelable(base::Bind(&HelperObject::IncrementNumber,
+                                           base::Unretained(&obj)));
+
+  base::Closure callback = cancelable.callback();
+  callback.Run();
+  EXPECT_EQ(1, obj.number());
+
+  callback.Run();
+  EXPECT_EQ(2, obj.number());
+
+  cancelable.Cancel();
+  callback.Run();
+  EXPECT_EQ(2, obj.number());
+}
+
+TEST(CancelableCallbackTest, NArity) {
+  HelperObject obj;
+  CancelableCallback cancelable(
+      base::Bind(&HelperObject::IncrementNumberBy, base::Unretained(&obj), 5));
+
+  base::Closure callback = cancelable.callback();
+  callback.Run();
+  EXPECT_EQ(5, obj.number());
+
+  callback.Run();
+  EXPECT_EQ(10, obj.number());
+
+  cancelable.Cancel();
+  callback.Run();
+  EXPECT_EQ(10, obj.number());
+}
+
+TEST(CancelableCallbackTest, Destruction) {

[groby-ooo-7-16, 2011/11/23 02:14:12]

CallbackCanceledOnDestruction would probably describe this better.

[James Hawkins, 2011/11/23 03:59:08]

Done.

+  HelperObject obj;
+  base::Closure callback;
+
+  {
+    CancelableCallback cancelable(base::Bind(&HelperObject::IncrementNumber,
+                                             base::Unretained(&obj)));
+
+    callback = cancelable.callback();
+    callback.Run();
+    EXPECT_EQ(1, obj.number());
+  }
+
+  callback.Run();
+  EXPECT_EQ(1, obj.number());
+}

[groby-ooo-7-16, 2011/11/23 02:14:12]

Can we add an example that uses PostTask? (Yes, it's fairly straightforward to
use. Still, it'd be nice)

[James Hawkins, 2011/11/23 03:59:08]

Done.

+
+}  // namespace
+}  // namespace base