Function-type templated CallbackRegistry

base/callback_registry.h

+// This file was GENERATED by command:
+//     pump.py callback_registry.h.pump
+// DO NOT EDIT BY HAND!!!
+
+
 // Copyright 2013 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.
 
 #ifndef BASE_CALLBACK_REGISTRY_H_
 #define BASE_CALLBACK_REGISTRY_H_
 
 #include <list>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
+#include "base/callback_internal.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 
 // OVERVIEW:
 //
 // A container for a list of callbacks.  Unlike a normal STL vector or list,
 // this container can be modified during iteration without invalidating the
 // iterator. It safely handles the case of a callback removing itself
 // or another callback from the list while callbacks are being run.
 //
 // TYPICAL USAGE:
 //
 // class MyWidget {
 //  public:
 //   ...
 //
 //   typedef base::Callback<void(const Foo&)> OnFooCallback;
 //
-//   scoped_ptr<base::CallbackRegistry<Foo>::Subscription> RegisterCallback(
-//       const OnFooCallback& cb) {
+//   scoped_ptr<base::CallbackRegistry<void(const Foo&)>::Subscription>
+//   RegisterCallback(const OnFooCallback& cb) {
 //     return callback_registry_.Add(cb);
 //   }
 //
 //  private:
 //   void NotifyFoo(const Foo& foo) {
 //      callback_registry_.Notify(foo);
 //   }
 //
-//   base::CallbackRegistry<Foo> callback_registry_;
+//   base::CallbackRegistry<void(const Foo&)> callback_registry_;
 // };
 //
 //
 // class MyWidgetListener {
 //  public:
 //   MyWidgetListener::MyWidgetListener() {
 //     foo_subscription_ = MyWidget::GetCurrent()->RegisterCallback(
 //             base::Bind(&MyWidgetListener::OnFoo, this)));
 //   }
 //
@@ skipping 114 matching lines @@
 
  private:
   std::list<CallbackType> callbacks_;
   int active_iterator_count_;
 
   DISALLOW_COPY_AND_ASSIGN(CallbackRegistryBase);
 };
 
 }  // namespace internal
 
-template <typename Details>
-class CallbackRegistry
-    : public internal::CallbackRegistryBase<Callback<void(const Details&)> > {
+template <typename Sig> class CallbackRegistry;

[erikwright (departed), 2013/09/17 18:21:49]

blank between decl and specialization.

[Cait (Slow), 2013/09/19 17:29:57]

Done.

+template <>
+class CallbackRegistry<void(void)>
+    : public internal::CallbackRegistryBase<Callback<void(void)> > {
  public:
+  typedef Callback<void(void)> CallbackType;
+
   CallbackRegistry() {}
 
-  // Execute all active callbacks with |details| parameter.
-  void Notify(const Details& details) {
-    typename internal::CallbackRegistryBase<
-        Callback<void(const Details&)> >::Iterator it = this->GetIterator();
-    Callback<void(const Details&)>* cb;
-    while((cb = it.GetNext()) != NULL) {
-      cb->Run(details);
-    }
-  }
-
-private:
-  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
-};
-
-template <> class CallbackRegistry<void>
-    : public internal::CallbackRegistryBase<Closure> {
- public:
-  CallbackRegistry() {}
-
-  // Execute all active callbacks.
   void Notify() {
-    Iterator it = this->GetIterator();
-    Closure* cb;
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
     while((cb = it.GetNext()) != NULL) {
       cb->Run();
     }
   }
 
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1>
+class CallbackRegistry<void(A1)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1)> > {
+ public:
+  typedef Callback<void(A1)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1) {

[erikwright (departed), 2013/09/17 18:21:49]

It will surprise no one to hear that I'm not a fan of reaching into
callback_internal.h here.

Suggestions:

1) Duplicate the subset of CallbackParamTraits that we want here.
2) Move CallbackParamTraits (or at least the ForwardType part) to
template_util.h . i.e., base::ParameterTraits::ForwardType or
base::ParameterForwardingType .
3) Make Callback<A1, ...> expose Callback<A1, ...>::A1ForwardType

I prefer (2) personally.

I'm OK to see that done in a separate follow-up CL, but I'd like to at least
hear ajwong's perspective first.

[awong, 2013/09/17 18:31:00]

I'm slammed right now between perf and a some outstanding CLs so I can't do the
full review but I'll respond to this point.

(1) is cute/paste which is worse than reaching into base::internal.
(3) is polluting the public API.

We could think about (2), but it's an odd set of behavior that really only makes
sense if you are wrapping callback...which people should generally avoid doing
anyways.

Given all this, I think using callback_internal.h is the right solution.

+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1, typename A2>
+class CallbackRegistry<void(A1, A2)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1, A2)> > {
+ public:
+  typedef Callback<void(A1, A2)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1,
+              typename internal::CallbackParamTraits<A2>::ForwardType a2) {
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1, a2);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1, typename A2, typename A3>
+class CallbackRegistry<void(A1, A2, A3)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1, A2, A3)> > {
+ public:
+  typedef Callback<void(A1, A2, A3)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1,
+              typename internal::CallbackParamTraits<A2>::ForwardType a2,
+              typename internal::CallbackParamTraits<A3>::ForwardType a3) {
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1, a2, a3);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1, typename A2, typename A3, typename A4>
+class CallbackRegistry<void(A1, A2, A3, A4)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1, A2, A3, A4)> > {
+ public:
+  typedef Callback<void(A1, A2, A3, A4)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1,
+              typename internal::CallbackParamTraits<A2>::ForwardType a2,
+              typename internal::CallbackParamTraits<A3>::ForwardType a3,
+              typename internal::CallbackParamTraits<A4>::ForwardType a4) {
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1, a2, a3, a4);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5>
+class CallbackRegistry<void(A1, A2, A3, A4, A5)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1, A2, A3, A4, A5)> > {
+ public:
+  typedef Callback<void(A1, A2, A3, A4, A5)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1,
+              typename internal::CallbackParamTraits<A2>::ForwardType a2,
+              typename internal::CallbackParamTraits<A3>::ForwardType a3,
+              typename internal::CallbackParamTraits<A4>::ForwardType a4,
+              typename internal::CallbackParamTraits<A5>::ForwardType a5) {
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1, a2, a3, a4, a5);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6>
+class CallbackRegistry<void(A1, A2, A3, A4, A5, A6)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1, A2, A3, A4, A5, A6)> > {
+ public:
+  typedef Callback<void(A1, A2, A3, A4, A5, A6)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1,
+              typename internal::CallbackParamTraits<A2>::ForwardType a2,
+              typename internal::CallbackParamTraits<A3>::ForwardType a3,
+              typename internal::CallbackParamTraits<A4>::ForwardType a4,
+              typename internal::CallbackParamTraits<A5>::ForwardType a5,
+              typename internal::CallbackParamTraits<A6>::ForwardType a6) {
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1, a2, a3, a4, a5, a6);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
+};
+
+template <typename A1, typename A2, typename A3, typename A4, typename A5,
+    typename A6, typename A7>
+class CallbackRegistry<void(A1, A2, A3, A4, A5, A6, A7)>
+    : public internal::CallbackRegistryBase<
+          Callback<void(A1, A2, A3, A4, A5, A6, A7)> > {
+ public:
+  typedef Callback<void(A1, A2, A3, A4, A5, A6, A7)> CallbackType;
+
+  CallbackRegistry() {}
+
+  void Notify(typename internal::CallbackParamTraits<A1>::ForwardType a1,
+              typename internal::CallbackParamTraits<A2>::ForwardType a2,
+              typename internal::CallbackParamTraits<A3>::ForwardType a3,
+              typename internal::CallbackParamTraits<A4>::ForwardType a4,
+              typename internal::CallbackParamTraits<A5>::ForwardType a5,
+              typename internal::CallbackParamTraits<A6>::ForwardType a6,
+              typename internal::CallbackParamTraits<A7>::ForwardType a7) {
+    typename internal::CallbackRegistryBase<CallbackType>::Iterator it =
+        this->GetIterator();
+    CallbackType* cb;
+    while((cb = it.GetNext()) != NULL) {
+      cb->Run(a1, a2, a3, a4, a5, a6, a7);
+    }
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(CallbackRegistry);
 };
 
 }  // namespace base
 
-#endif  // BASE_CALLBACK_REGISTRY_H_
+#endif  // BASE_CALLBACK_REGISTRY_H