Template methods on Timer classes instead of the classes themselves.

base/timer/timer.h

 // Copyright (c) 2012 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.
 
 // OneShotTimer and RepeatingTimer provide a simple timer API.  As the names
 // suggest, OneShotTimer calls you back once after a time delay expires.
 // RepeatingTimer on the other hand calls you back periodically with the
 // prescribed time interval.
 //
 // OneShotTimer and RepeatingTimer both cancel the timer when they go out of
@@ skipping 11 matching lines @@
 //                    this, &MyClass::DoStuff);
 //     }
 //     void StopDoingStuff() {
 //       timer_.Stop();
 //     }
 //    private:
 //     void DoStuff() {
 //       // This method is called every second to do stuff.
 //       ...
 //     }
-//     base::RepeatingTimer<MyClass> timer_;
+//     base::RepeatingTimer timer_;
 //   };
 //
 // Both OneShotTimer and RepeatingTimer also support a Reset method, which
 // allows you to easily defer the timer event until the timer delay passes once
 // again.  So, in the above example, if 0.5 seconds have already passed,
 // calling Reset on timer_ would postpone DoStuff by another 1 second.  In
 // other words, Reset is shorthand for calling Stop and then Start again with
 // the same arguments.
 //
 // NOTE: These APIs are not thread safe. Always call from the same thread.
@@ skipping 150 matching lines @@
 
   // If true, user_task_ is scheduled to run sometime in the future.
   bool is_running_;
 
   DISALLOW_COPY_AND_ASSIGN(Timer);
 };
 
 //-----------------------------------------------------------------------------
 // This class is an implementation detail of OneShotTimer and RepeatingTimer.
 // Please do not use this class directly.
-template <class Receiver, bool kIsRepeating>
 class BaseTimerMethodPointer : public Timer {
  public:
-  typedef void (Receiver::*ReceiverMethod)();
-
   // This is here to work around the fact that Timer::Start is "hidden" by the
   // Start definition below, rather than being overloaded.
   // TODO(tim): We should remove uses of BaseTimerMethodPointer::Start below
   // and convert callers to use the base::Closure version in Timer::Start,
   // see bug 148832.
   using Timer::Start;
 
-  BaseTimerMethodPointer() : Timer(kIsRepeating, kIsRepeating) {}
+  enum RepeatMode { ONE_SHOT, REPEATING };
+  BaseTimerMethodPointer(RepeatMode mode)
+      : Timer(mode == REPEATING, mode == REPEATING) {}
 
   // Start the timer to run at the given |delay| from now. If the timer is
   // already running, it will be replaced to call a task formed from
   // |reviewer->*method|.
-  virtual void Start(const tracked_objects::Location& posted_from,
-                     TimeDelta delay,
-                     Receiver* receiver,
-                     ReceiverMethod method) {
+  template <class Receiver>
+  void Start(const tracked_objects::Location& posted_from,
+             TimeDelta delay,
+             Receiver* receiver,
+             void (Receiver::*method)()) {
     Timer::Start(posted_from, delay,
                  base::Bind(method, base::Unretained(receiver)));
   }
 };
 
 //-----------------------------------------------------------------------------
 // A simple, one-shot timer.  See usage notes at the top of the file.
-template <class Receiver>
-class OneShotTimer : public BaseTimerMethodPointer<Receiver, false> {};
+class OneShotTimer : public BaseTimerMethodPointer {
+ public:
+  OneShotTimer() : BaseTimerMethodPointer(ONE_SHOT) {}
+};
 
 //-----------------------------------------------------------------------------
 // A simple, repeating timer.  See usage notes at the top of the file.
-template <class Receiver>
-class RepeatingTimer : public BaseTimerMethodPointer<Receiver, true> {};
+class RepeatingTimer : public BaseTimerMethodPointer {
+ public:
+  RepeatingTimer() : BaseTimerMethodPointer(REPEATING) {}
+};
 
 //-----------------------------------------------------------------------------
 // A Delay timer is like The Button from Lost. Once started, you have to keep
 // calling Reset otherwise it will call the given method in the MessageLoop
 // thread.
 //
 // Once created, it is inactive until Reset is called. Once |delay| seconds have
 // passed since the last call to Reset, the callback is made. Once the callback
 // has been made, it's inactive until Reset is called again.
 //
 // If destroyed, the timeout is canceled and will not occur even if already
 // inflight.
-template <class Receiver>
-class DelayTimer : protected Timer {
+class BASE_EXPORT DelayTimer : protected Timer {
  public:
-  typedef void (Receiver::*ReceiverMethod)();
-
-  DelayTimer(const tracked_objects::Location& posted_from,
-             TimeDelta delay,
-             Receiver* receiver,
-             ReceiverMethod method)
-      : Timer(posted_from, delay,
+  template <class Receiver>
+  BASE_EXPORT DelayTimer(const tracked_objects::Location& posted_from,

[Nico, 2015/09/23 00:21:25]

Huh, that's really needed? Surprising, given that the class already has this…

[danakj, 2015/09/23 19:00:32]

Ya.. compiler complains both with and without this. For others following along:

Without this it says it can't find the method at link time, cuz the class is
exported so it expects to find everything at linking. (MSVC only).

With this it fails too, for even better reasons it doesn't make sense to export
templates.

Nico gave me the idea to just export Reset since it's the whole reason for this
problem as it's virtual and clang-plugin makes me move it to the .cc so it
requires export. So trying that on the bots now.

+                         TimeDelta delay,
+                         Receiver* receiver,
+                         void (Receiver::*method)())
+      : Timer(posted_from,
+              delay,
               base::Bind(method, base::Unretained(receiver)),
               false) {}
 
-  void Reset() override { Timer::Reset(); }
+  void Reset() override;
 };
 
 }  // namespace base
 
 #endif  // BASE_TIMER_TIMER_H_