[libsigc++2/variadic] Functors: Do not derive from functor_base.

[Murray Cumming <murrayc src gnome org>]

commit c0beabc7e02bd5a44860a394ece24e53be4301bc
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Jan 15 23:51:06 2016 +0100

    Functors: Do not derive from functor_base.
    
    Because we don't need result_type any more.

 sigc++/adaptors/adaptor_base.h      |    5 +--
 sigc++/functors/functor_trait.h     |   53 -----------------------------------
 sigc++/functors/macros/mem_fun.h.m4 |    2 +-
 sigc++/functors/ptr_fun.h           |    2 +-
 sigc++/functors/slot_base.h         |    2 +-
 tests/test_bind.cc                  |    4 +-
 tests/test_compose.cc               |    3 --
 tests/test_exception_catch.cc       |    6 ++--
 tests/test_hide.cc                  |    6 +--
 tests/test_retype_return.cc         |    4 +-
 tests/test_track_obj.cc             |    4 +-
 11 files changed, 15 insertions(+), 76 deletions(-)
---
diff --git a/sigc++/adaptors/adaptor_base.h b/sigc++/adaptors/adaptor_base.h
index 97b6f68..6cb71c7 100644
--- a/sigc++/adaptors/adaptor_base.h
+++ b/sigc++/adaptors/adaptor_base.h
@@ -9,9 +9,6 @@ namespace sigc {
  * Functors which have all methods based on templates
  * should publicly inherit from this hint.
  *
- * adaptor_base inherits from the functor_base hint so
- * derived types should also have a result_type defined.
- *
  * Adaptors don't inherit from this type directly. They use
  * use sigc::adapts as a base type instead. sigc::adaptors
  * wraps arbitrary functor types as well as function pointers
@@ -19,7 +16,7 @@ namespace sigc {
  *
  * @ingroup adaptors
  */
-struct adaptor_base : public functor_base {};
+struct adaptor_base {};
 
 } /* namespace sigc */
 #endif /* _SIGC_ADAPTORS_DEDUCE_RESULT_TYPE_H_ */
diff --git a/sigc++/functors/functor_trait.h b/sigc++/functors/functor_trait.h
index 54240be..8a54186 100644
--- a/sigc++/functors/functor_trait.h
+++ b/sigc++/functors/functor_trait.h
@@ -55,17 +55,8 @@ struct nil {};
  * and you want them to be implicitly convertible into slots, libsigc++ must know
  * the result type of your functors. There are different ways to achieve that.
  *
- * - Derive your functors from sigc::functor_base and place
- *   <tt>typedef T_return result_type;</tt> in the class definition.
  * - Use the macro SIGC_FUNCTOR_TRAIT(T_functor,T_return) in namespace sigc.
  *   Multi-type functors are only partly supported.
- * - For functors not derived from sigc::functor_base, and not specified with
- *   SIGC_FUNCTOR_TRAIT(), libsigc++ tries to deduce the result type with the
- *   C++11 decltype() specifier. That attempt usually succeeds if the functor
- *   has a single operator()(), but it fails if operator()() is overloaded.
- * - Use the macro #SIGC_FUNCTORS_HAVE_RESULT_TYPE, if you want libsigc++ to assume
- *   that result_type is defined in all user-defined or third party functors,
- *   whose result type can't be deduced in any other way.
  *
  * If all these ways to deduce the result type fail, void is assumed.
  *
@@ -147,50 +138,6 @@ struct functor_trait<T_functor, false, true>
 };
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 
-/** Helper macro, if you want to mix user-defined and third party functors with libsigc++.
- *
- * If you want to mix functors not derived from sigc::functor_base with libsigc++, and
- * these functors define @p result_type, use this macro inside namespace sigc like so:
- * @code
- * namespace sigc { SIGC_FUNCTORS_HAVE_RESULT_TYPE }
- * @endcode
- *
- * @ingroup sigcfunctors
- */
-#define SIGC_FUNCTORS_HAVE_RESULT_TYPE                 \
-template <class T_functor>                             \
-struct functor_trait<T_functor, false, false>          \
-{                                                      \
-  typedef T_functor functor_type;                      \
-};
-
-/** Helper macro, if you want to mix user-defined and third party functors with libsigc++.
- *
- * If you want to mix functors not derived from sigc::functor_base with libsigc++, and
- * these functors don't define @p result_type, use this macro inside namespace sigc
- * to expose the return type of the functors like so:
- * @code
- * namespace sigc {
- *   SIGC_FUNCTOR_TRAIT(first_functor_type, return_type_of_first_functor_type)
- *   SIGC_FUNCTOR_TRAIT(second_functor_type, return_type_of_second_functor_type)
- *   ...
- * }
- * @endcode
- *
- * @ingroup sigcfunctors
- */
-#define SIGC_FUNCTOR_TRAIT(T_functor,T_return) \
-template <>                                    \
-struct functor_trait<T_functor, false, false>  \
-{                                              \
-  typedef T_functor functor_type;              \
-};                                             \
-template <>                                    \
-struct functor_trait<T_functor, false, true>   \
-{                                              \
-  typedef T_functor functor_type;              \
-};
-
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 // detect the the functor version of non-functor types.
diff --git a/sigc++/functors/macros/mem_fun.h.m4 b/sigc++/functors/macros/mem_fun.h.m4
index ca9051f..551fd22 100644
--- a/sigc++/functors/macros/mem_fun.h.m4
+++ b/sigc++/functors/macros/mem_fun.h.m4
@@ -30,7 +30,7 @@ define([MEMBER_FUNCTOR],[dnl
  * @ingroup mem_fun
  */
 template <class T_return, class T_obj, class... T_arg>
-class [$1]mem_functor : public functor_base
+class [$1]mem_functor
 {
 public:
   typedef T_return (T_obj::*function_type)(T_arg...) $3;
diff --git a/sigc++/functors/ptr_fun.h b/sigc++/functors/ptr_fun.h
index 41eb85f..63f4b43 100644
--- a/sigc++/functors/ptr_fun.h
+++ b/sigc++/functors/ptr_fun.h
@@ -50,7 +50,7 @@ namespace sigc {
  * @ingroup ptr_fun
  */
 template <class T_return, class... T_args>
-class pointer_functor : public functor_base
+class pointer_functor
 {
   using function_type = T_return (*)(T_args...);
 protected: 
diff --git a/sigc++/functors/slot_base.h b/sigc++/functors/slot_base.h
index 8ecd086..9b9a5d4 100644
--- a/sigc++/functors/slot_base.h
+++ b/sigc++/functors/slot_base.h
@@ -240,7 +240,7 @@ struct SIGC_API slot_do_unbind
  *
  * @ingroup slot
  */
-class SIGC_API slot_base : public functor_base
+class SIGC_API slot_base
 {
   typedef internal::slot_rep rep_type;
 
diff --git a/tests/test_bind.cc b/tests/test_bind.cc
index 3ab7cf6..57486bd 100644
--- a/tests/test_bind.cc
+++ b/tests/test_bind.cc
@@ -15,7 +15,7 @@ namespace
 {
 std::ostringstream result_stream;
 
-struct foo : public sigc::functor_base
+struct foo
 {
   // choose a type that can hold all return values
   typedef int result_type;
@@ -39,7 +39,7 @@ struct foo : public sigc::functor_base
   }
 };
 
-struct foo_void : public sigc::functor_base
+struct foo_void
 {
   typedef void result_type;
 
diff --git a/tests/test_compose.cc b/tests/test_compose.cc
index a626ba6..132f413 100644
--- a/tests/test_compose.cc
+++ b/tests/test_compose.cc
@@ -8,9 +8,6 @@
 #include <sstream>
 #include <cstdlib>
 
-// assume existance of T_functor::result_type for unknown functor types:
-namespace sigc { SIGC_FUNCTORS_HAVE_RESULT_TYPE }
-
 namespace
 {
 std::ostringstream result_stream;
diff --git a/tests/test_exception_catch.cc b/tests/test_exception_catch.cc
index 6ae7e51..8e4ac28 100644
--- a/tests/test_exception_catch.cc
+++ b/tests/test_exception_catch.cc
@@ -13,7 +13,7 @@ namespace
 {
 std::ostringstream result_stream;
 
-struct f : public sigc::functor_base
+struct f
 {
   typedef int result_type;
 
@@ -24,7 +24,7 @@ struct f : public sigc::functor_base
   }
 };
 
-struct g : public sigc::functor_base
+struct g
 {
   typedef int result_type;
 
@@ -35,7 +35,7 @@ struct g : public sigc::functor_base
   }
 };
 
-struct g_void : public sigc::functor_base
+struct g_void
 {
   typedef void result_type;
 
diff --git a/tests/test_hide.cc b/tests/test_hide.cc
index c1cdad2..1f53d50 100644
--- a/tests/test_hide.cc
+++ b/tests/test_hide.cc
@@ -12,7 +12,7 @@ namespace
 {
 std::ostringstream result_stream;
 
-struct foo : public sigc::functor_base
+struct foo
 {
   // choose a type that can hold all return values
   typedef int result_type;
@@ -30,7 +30,7 @@ struct foo : public sigc::functor_base
   }
 };
 
-struct foo_void : public sigc::functor_base
+struct foo_void
 {
   typedef void result_type;
 
@@ -42,8 +42,6 @@ struct foo_void : public sigc::functor_base
 
 } // end anonymous namespace
 
-namespace sigc { SIGC_FUNCTOR_TRAIT(foo,bool) }
-
 int main(int argc, char* argv[])
 {
   auto util = TestUtilities::get_instance();
diff --git a/tests/test_retype_return.cc b/tests/test_retype_return.cc
index 9026e32..259d71e 100644
--- a/tests/test_retype_return.cc
+++ b/tests/test_retype_return.cc
@@ -13,7 +13,7 @@ namespace
 {
 std::ostringstream result_stream;
 
-struct foo : public sigc::functor_base
+struct foo
 {
   typedef float result_type;
 
@@ -30,7 +30,7 @@ struct foo : public sigc::functor_base
   }
 };
 
-struct bar : public sigc::trackable, public sigc::functor_base
+struct bar : public sigc::trackable
 {
   typedef int result_type;
 
diff --git a/tests/test_track_obj.cc b/tests/test_track_obj.cc
index 635be0c..bd39a67 100644
--- a/tests/test_track_obj.cc
+++ b/tests/test_track_obj.cc
@@ -59,7 +59,7 @@ struct bar_group4 : public sigc::trackable
 {
 };
 
-class Functor1 : public sigc::functor_base
+class Functor1
 {
 public:
   typedef std::string result_type;
@@ -76,7 +76,7 @@ private:
   const bar_group4& bar_;
 };
 
-class Functor2 : public sigc::functor_base
+class Functor2
 {
 public:
   typedef std::string result_type;