[libsigcplusplus/variadic_mem_fun3: 97/148] slot_rep::dup(): Take a slot_rep* instead of void*.

[Murray Cumming <murrayc src gnome org>]

commit 7c8fafbd2f81ab3e357f5b4caa3f7050d533b2b2
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Mar 3 11:49:16 2016 +0100

    slot_rep::dup(): Take a slot_rep* instead of void*.

 sigc++/functors/slot.h      |    5 ++---
 sigc++/functors/slot_base.h |    7 +++++--
 2 files changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/sigc++/functors/slot.h b/sigc++/functors/slot.h
index ea793c7..dfbc4eb 100644
--- a/sigc++/functors/slot.h
+++ b/sigc++/functors/slot.h
@@ -74,10 +74,9 @@ struct typed_slot_rep : public slot_rep
    * slot_rep object is registered in the referred trackables.
    * @return A deep copy of the slot_rep object.
    */
-  static void* dup(void* data)
+  static slot_rep* dup(slot_rep* a_rep)
     {
-      slot_rep* a_rep = reinterpret_cast<slot_rep*>(data);
-      return static_cast<slot_rep*>(new self(*static_cast<self*>(a_rep)));
+      return new self(*static_cast<self*>(a_rep));
     }
 };
 
diff --git a/sigc++/functors/slot_base.h b/sigc++/functors/slot_base.h
index 61c1d79..9e6ef47 100644
--- a/sigc++/functors/slot_base.h
+++ b/sigc++/functors/slot_base.h
@@ -63,6 +63,7 @@ struct SIGC_API slot_rep : public trackable
   /* NB: Instead of slot_rep we could inherit slot_base from trackable.
    * However, a simple benchmark seems to indicate that this slows
    * down dereferencing of slot list iterators. Martin. */
+  //TODO: Try this now? murrayc.
 
   /// Callback that invokes the contained functor.
   /* This can't be a virtual function since number of arguments
@@ -77,10 +78,12 @@ struct SIGC_API slot_rep : public trackable
    */
   func_destroy_notify destroy_;
 
+  typedef slot_rep* (*hook_dup)(slot_rep*);
+
   /** Callback that makes a deep copy of the slot_rep object.
    * @return A deep copy of the slot_rep object.
    */
-  hook dup_;
+  hook_dup dup_;
 
   /** Callback of parent_. */
   func_destroy_notify cleanup_;
@@ -88,7 +91,7 @@ struct SIGC_API slot_rep : public trackable
   /** Parent object whose callback cleanup_ is executed on notification. */
   notifiable* parent_;
 
-  inline slot_rep(hook call__, notifiable::func_destroy_notify destroy__, hook dup__) noexcept
+  inline slot_rep(hook call__, notifiable::func_destroy_notify destroy__, hook_dup dup__) noexcept
     : call_(call__), destroy_(destroy__), dup_(dup__), cleanup_(nullptr), parent_(nullptr) {}
 
   inline ~slot_rep()