Retry 114494 - Remove BindStateHolder and have Bind() return a Callback<> object directly."

This removes some complexity and also fixes a bug where if you call Bind() with the result of Bind(), the resulting Callback would only be valid during the first call. Ouch.

Also makes the static type checking a bit more strict when assigning into a Callback<>.

BUG=none
TEST=new unittests

Review URL: http://codereview.chromium.org/8915024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@115045 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 29 insertions, 7 deletions

diff --git a/base/callback_unittest.cc b/base/callback_unittest.cc
index 8527e70..e42b933 100644
--- a/base/callback_unittest.cc
+++ b/base/callback_unittest.cc
@@ -9,6 +9,7 @@
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
+
 namespace {
 
 class HelperObject {
@@ -26,18 +27,40 @@ struct FakeInvoker {
   static void Run(internal::BindStateBase*) {
   }
 };
+}  // namespace
+
+namespace internal {
+template <typename Runnable, typename RunType, typename BoundArgsType>
+struct BindState;
 
 // White-box testpoints to inject into a Callback<> object for checking
-// comparators and emptiness APIs.
-class FakeBindState1 : public internal::BindStateBase {
+// comparators and emptiness APIs.  Use a BindState that is specialized
+// based on a type we declared in the anonymous namespace above to remove any
+// chance of colliding with another instantiation and breaking the
+// one-definition-rule.
+template <>
+struct BindState<void(void), void(void), void(FakeInvoker)>
+    : public BindStateBase {
  public:
   typedef FakeInvoker InvokerType;
 };
 
-class FakeBindState2 : public internal::BindStateBase {
+template <>
+struct BindState<void(void), void(void),
+                           void(FakeInvoker, FakeInvoker)>
+    : public BindStateBase {
  public:
   typedef FakeInvoker InvokerType;
 };
+}  // namespace internal
+
+namespace {
+
+typedef internal::BindState<void(void), void(void), void(FakeInvoker)>
+    FakeBindState1;
+typedef internal::BindState<void(void), void(void),
+                            void(FakeInvoker, FakeInvoker)>
+   FakeBindState2;
 
 TEST(CallbackOld, OneArg) {
   HelperObject obj;
@@ -60,8 +83,8 @@ TEST(CallbackOld, ReturnValue) {
 class CallbackTest : public ::testing::Test {
  public:
   CallbackTest()
-      : callback_a_(MakeBindStateHolder(new FakeBindState1())),
-        callback_b_(MakeBindStateHolder(new FakeBindState2())) {
+      : callback_a_(new FakeBindState1()),
+        callback_b_(new FakeBindState2()) {
   }
 
   virtual ~CallbackTest() {
@@ -105,8 +128,7 @@ TEST_F(CallbackTest, Equals) {
   EXPECT_FALSE(callback_b_.Equals(callback_a_));
 
   // We should compare based on instance, not type.
-  Callback<void(void)> callback_c(
-      MakeBindStateHolder(new FakeBindState1()));
+  Callback<void(void)> callback_c(new FakeBindState1());
   Callback<void(void)> callback_a2 = callback_a_;
   EXPECT_TRUE(callback_a_.Equals(callback_a2));
   EXPECT_FALSE(callback_a_.Equals(callback_c));