DPL: move can_assign helper to the only used place

Author: ktf

Framework/Core/include/Framework/TypeTraits.h

@@ -220,38 +220,5 @@ struct is_boost_serializable<Type, boost::archive::binary_oarchive, std::void_t<
   : is_boost_serializable<typename Type::value_type, boost::archive::binary_oarchive> {
 };
 
-/// Helper to get the corresponding std::function type for a callable object
-/// the default is void
-template <typename T>
-struct get_function {
-  using type = void;
-};
-
-/// the matching specialization builds the function type from the return type
-/// and types in the argument pack
-template <typename Ret, typename Class, typename... Args>
-struct get_function<Ret (Class::*)(Args...) const> {
-  using type = std::function<Ret(Args...)>;
-};
-
-/// check if a lambda can be assigned to concrete std::function
-/// default is false
-template <typename From, typename To, typename _ = void>
-struct can_assign : public std::false_type {
-};
-
-/// specialize for callable types, i.e. having operator(), the 'From' type can be
-/// assigned if its corresponding function type is the same as 'To' type
-/// a direct comparison is not possible because lambdas are their own type
-template <typename From, typename To>
-struct can_assign<
-  From, To,
-  std::conditional_t<
-    false,
-    class_member_checker<
-      decltype(&From::operator())>,
-    void>> : public std::is_same<typename get_function<decltype(&From::operator())>::type, To> {
-};
-
 } // namespace o2::framework
 #endif // FRAMEWORK_TYPETRAITS_H

Framework/Core/test/test_TypeTraits.cxx

@@ -141,20 +141,3 @@ BOOST_AUTO_TEST_CASE(TestIsSpan)
   BOOST_REQUIRE_EQUAL(is_span<decltype(b)>::value, false);
   BOOST_REQUIRE_EQUAL(is_span<decltype(c)>::value, false);
 }
-
-BOOST_AUTO_TEST_CASE(TestCanAssign)
-{
-  using Callback = std::function<bool(int, float)>;
-  auto matching = [](int, float) -> bool {
-    return true;
-  };
-  auto otherReturn = [](int, float) -> int {
-    return 0;
-  };
-  auto otherParam = [](int, int) -> bool {
-    return true;
-  };
-  BOOST_REQUIRE((can_assign<decltype(matching), Callback>::value == true));
-  BOOST_REQUIRE((can_assign<decltype(otherReturn), Callback>::value == false));
-  BOOST_REQUIRE((can_assign<decltype(otherParam), Callback>::value == false));
-}

Framework/Utils/include/DPLUtils/RootTreeWriter.h

@@ -40,6 +40,39 @@ namespace o2
 namespace framework
 {
 
+/// Helper to get the corresponding std::function type for a callable object
+/// the default is void
+template <typename T>
+struct get_function {
+  using type = void;
+};
+
+/// the matching specialization builds the function type from the return type
+/// and types in the argument pack
+template <typename Ret, typename Class, typename... Args>
+struct get_function<Ret (Class::*)(Args...) const> {
+  using type = std::function<Ret(Args...)>;
+};
+
+/// check if a lambda can be assigned to concrete std::function
+/// default is false
+template <typename From, typename To, typename _ = void>
+struct can_assign : public std::false_type {
+};
+
+/// specialize for callable types, i.e. having operator(), the 'From' type can be
+/// assigned if its corresponding function type is the same as 'To' type
+/// a direct comparison is not possible because lambdas are their own type
+template <typename From, typename To>
+struct can_assign<
+  From, To,
+  std::conditional_t<
+    false,
+    class_member_checker<
+      decltype(&From::operator())>,
+    void>> : public std::is_same<typename get_function<decltype(&From::operator())>::type, To> {
+};
+
 /// @class RootTreeWriter
 /// @brief A generic writer interface for ROOT TTree objects.
 ///

Framework/Utils/test/test_RootTreeWriter.cxx

@@ -308,4 +308,21 @@ BOOST_AUTO_TEST_CASE(test_RootTreeWriterSpec_store_types)
   // pointer type used as store type
   static_assert(std::is_same<Trait<std::vector<Polymorphic>>::store_type, std::vector<Polymorphic>*>::value == true);
 }
+
+BOOST_AUTO_TEST_CASE(TestCanAssign)
+{
+  using Callback = std::function<bool(int, float)>;
+  auto matching = [](int, float) -> bool {
+    return true;
+  };
+  auto otherReturn = [](int, float) -> int {
+    return 0;
+  };
+  auto otherParam = [](int, int) -> bool {
+    return true;
+  };
+  BOOST_REQUIRE((can_assign<decltype(matching), Callback>::value == true));
+  BOOST_REQUIRE((can_assign<decltype(otherReturn), Callback>::value == false));
+  BOOST_REQUIRE((can_assign<decltype(otherParam), Callback>::value == false));
+}
 } // namespace o2::test