Template methods on Timer classes instead of the classes themselves.

base/timer/timer.h

Index: base/timer/timer.h
diff --git a/base/timer/timer.h b/base/timer/timer.h
index 1ef58a3ea0b30a23dcd3fdc90a03675abea2fabf..e083bf5a253c3876d1c4a7c119de48afbf32da14 100644
--- a/base/timer/timer.h
+++ b/base/timer/timer.h
@@ -29,7 +29,7 @@
 //       // 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
@@ -200,11 +200,8 @@ class BASE_EXPORT 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
@@ -212,15 +209,18 @@ class BaseTimerMethodPointer : public Timer {
   // 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)));
   }
@@ -228,13 +228,17 @@ class BaseTimerMethodPointer : public Timer {
 
 //-----------------------------------------------------------------------------
 // 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
@@ -247,20 +251,19 @@ class RepeatingTimer : public BaseTimerMethodPointer<Receiver, true> {};
 //
 // 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