Moarrrr templates! Remove some boilerplate in embind. Thanks imran and andy!

2 files changed, 28 insertions, 1 deletions

diff --git a/system/include/emscripten/bind.h b/system/include/emscripten/bind.h
index 1be35826..7bc28ff6 100644
--- a/system/include/emscripten/bind.h
+++ b/system/include/emscripten/bind.h
@@ -282,6 +282,33 @@ namespace emscripten {
         return method;
     }
 
+    namespace internal {        
+        // this should be in <type_traits>, but alas, it's not
+        template<typename T> struct remove_class;
+        template<typename C, typename R, typename... A>
+        struct remove_class<R(C::*)(A...)> { using type = R(A...); };
+        template<typename C, typename R, typename... A>
+        struct remove_class<R(C::*)(A...) const> { using type = R(A...); };
+        template<typename C, typename R, typename... A>
+        struct remove_class<R(C::*)(A...) volatile> { using type = R(A...); };
+        template<typename C, typename R, typename... A>
+        struct remove_class<R(C::*)(A...) const volatile> { using type = R(A...); };
+
+        template<typename LambdaType>
+        struct CalculateLambdaSignature {
+            using type = typename std::add_pointer<
+                typename remove_class<
+                    decltype(&LambdaType::operator())
+                >::type
+            >::type;
+        };
+    }
+
+    template<typename LambdaType>
+    typename internal::CalculateLambdaSignature<LambdaType>::type optional_override(const LambdaType& fp) {
+        return fp;
+    }
+
     ////////////////////////////////////////////////////////////////////////////////
     // Invoker
     ////////////////////////////////////////////////////////////////////////////////
diff --git a/tests/embind/embind_test.cpp b/tests/embind/embind_test.cpp
index a0cb858d..30267994 100644
--- a/tests/embind/embind_test.cpp
+++ b/tests/embind/embind_test.cpp
@@ -1226,7 +1226,7 @@ EMSCRIPTEN_BINDINGS(interface_tests) {
         .function("abstractMethod", &AbstractClass::abstractMethod, pure_virtual())
         // The select_overload is necessary because, otherwise, the C++ compiler
         // cannot deduce the signature of the lambda function.
-        .function("optionalMethod", select_overload<std::string(AbstractClass&, std::string)>(
+        .function("optionalMethod", optional_override(
             [](AbstractClass& this_, std::string s) {
                 return this_.AbstractClass::optionalMethod(s);
             }