[gin] Use variadic templates in gin/function_template.h

Replace pump.py generated gin/function_template.h with variadic template version.

This results in a concise code which does not require the use
of pump preprocessor.
Similar effort for base/callback.h is happening in https://codereview.chromium.org/610423003/

BUG=

Review URL: https://codereview.chromium.org/671433004

Cr-Commit-Position: refs/heads/master@{#301089}

3 files changed, 74 insertions, 590 deletions

diff --git a/gin/function_template.h b/gin/function_template.h
index 7ba54b5..955ff53 100644
--- a/gin/function_template.h
+++ b/gin/function_template.h
@@ -1,16 +1,10 @@
-// This file was GENERATED by command:
-//     pump.py function_template.h.pump
-// DO NOT EDIT BY HAND!!!
-
-
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
 
 #ifndef GIN_FUNCTION_TEMPLATE_H_
 #define GIN_FUNCTION_TEMPLATE_H_
 
-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
 #include "base/callback.h"
 #include "base/logging.h"
 #include "gin/arguments.h"
@@ -80,180 +74,6 @@ class CallbackHolder : public CallbackHolderBase {
   DISALLOW_COPY_AND_ASSIGN(CallbackHolder);
 };
 
-
-// This set of templates invokes a base::Callback, converts the return type to a
-// JavaScript value, and returns that value to script via the provided
-// gin::Arguments object.
-//
-// In C++, you can declare the function foo(void), but you can't pass a void
-// expression to foo. As a result, we must specialize the case of Callbacks that
-// have the void return type.
-template<typename R, typename P1 = void, typename P2 = void,
-    typename P3 = void, typename P4 = void, typename P5 = void,
-    typename P6 = void>
-struct Invoker {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3, P4, P5, P6)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5,
-      const P6& a6) {
-    args->Return(callback.Run(a1, a2, a3, a4, a5, a6));
-  }
-};
-template<typename P1, typename P2, typename P3, typename P4, typename P5,
-    typename P6>
-struct Invoker<void, P1, P2, P3, P4, P5, P6> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3, P4, P5, P6)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5,
-      const P6& a6) {
-    callback.Run(a1, a2, a3, a4, a5, a6);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4,
-    typename P5>
-struct Invoker<R, P1, P2, P3, P4, P5, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3, P4, P5)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5) {
-    args->Return(callback.Run(a1, a2, a3, a4, a5));
-  }
-};
-template<typename P1, typename P2, typename P3, typename P4, typename P5>
-struct Invoker<void, P1, P2, P3, P4, P5, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3, P4, P5)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4,
-      const P5& a5) {
-    callback.Run(a1, a2, a3, a4, a5);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3, typename P4>
-struct Invoker<R, P1, P2, P3, P4, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3, P4)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4) {
-    args->Return(callback.Run(a1, a2, a3, a4));
-  }
-};
-template<typename P1, typename P2, typename P3, typename P4>
-struct Invoker<void, P1, P2, P3, P4, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3, P4)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3,
-      const P4& a4) {
-    callback.Run(a1, a2, a3, a4);
-  }
-};
-
-template<typename R, typename P1, typename P2, typename P3>
-struct Invoker<R, P1, P2, P3, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2, P3)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3) {
-    args->Return(callback.Run(a1, a2, a3));
-  }
-};
-template<typename P1, typename P2, typename P3>
-struct Invoker<void, P1, P2, P3, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2, P3)>& callback,
-      const P1& a1,
-      const P2& a2,
-      const P3& a3) {
-    callback.Run(a1, a2, a3);
-  }
-};
-
-template<typename R, typename P1, typename P2>
-struct Invoker<R, P1, P2, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1, P2)>& callback,
-      const P1& a1,
-      const P2& a2) {
-    args->Return(callback.Run(a1, a2));
-  }
-};
-template<typename P1, typename P2>
-struct Invoker<void, P1, P2, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1, P2)>& callback,
-      const P1& a1,
-      const P2& a2) {
-    callback.Run(a1, a2);
-  }
-};
-
-template<typename R, typename P1>
-struct Invoker<R, P1, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R(P1)>& callback,
-      const P1& a1) {
-    args->Return(callback.Run(a1));
-  }
-};
-template<typename P1>
-struct Invoker<void, P1, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void(P1)>& callback,
-      const P1& a1) {
-    callback.Run(a1);
-  }
-};
-
-template<typename R>
-struct Invoker<R, void, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R()>& callback) {
-    args->Return(callback.Run());
-  }
-};
-template<>
-struct Invoker<void, void, void, void, void, void, void> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void()>& callback) {
-    callback.Run();
-  }
-};
-
-
 template<typename T>
 bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
                      T* result) {
@@ -284,170 +104,88 @@ inline bool GetNextArgument(Arguments* args, int create_flags,
   return true;
 }
 
+// Classes for generating and storing an argument pack of integer indices
+// (based on well-known "indices trick", see: http://goo.gl/bKKojn):
+template <size_t... indices>
+struct IndicesHolder {};
 
-// DispatchToCallback converts all the JavaScript arguments to C++ types and
-// invokes the base::Callback.
-template<typename Sig>
-struct Dispatcher {
+template <size_t requested_index, size_t... indices>
+struct IndicesGenerator {
+  using type = typename IndicesGenerator<requested_index - 1,
+                                         requested_index - 1,
+                                         indices...>::type;
 };
-
-template<typename R>
-struct Dispatcher<R()> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R()> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    Invoker<R>::Go(&args, holder->callback);
-  }
+template <size_t... indices>
+struct IndicesGenerator<0, indices...> {
+  using type = IndicesHolder<indices...>;
 };
 
-template<typename R, typename P1>
-struct Dispatcher<R(P1)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
+// Class template for extracting and storing single argument for callback
+// at position |index|.
+template <size_t index, typename ArgType>
+struct ArgumentHolder {
+  using ArgLocalType = typename CallbackParamTraits<ArgType>::LocalType;
 
-    typedef CallbackHolder<R(P1)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    if (!GetNextArgument(&args, holder->flags, true, &a1)) {
-      args.ThrowError();
-      return;
-    }
+  ArgLocalType value;
+  bool ok;
 
-    Invoker<R, P1>::Go(&args, holder->callback, a1);
+  ArgumentHolder(Arguments* args, int create_flags)
+      : ok(GetNextArgument(args, create_flags, index == 0, &value)) {
+    if (!ok)
+      args->ThrowError();
   }
 };
 
-template<typename R, typename P1, typename P2>
-struct Dispatcher<R(P1, P2)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
+// Class template for converting arguments from JavaScript to C++ and running
+// the callback with them.
+template <typename IndicesType, typename... ArgTypes>
+class Invoker {};
 
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2)) {
-      args.ThrowError();
-      return;
-    }
+template <size_t... indices, typename... ArgTypes>
+class Invoker<IndicesHolder<indices...>, ArgTypes...>
+    : public ArgumentHolder<indices, ArgTypes>... {
+ public:
+  // Invoker<> inherits from ArgumentHolder<> for each argument.
+  // C++ has always been strict about the class initialization order,
+  // so it is guaranteed ArgumentHolders will be initialized (and thus, will
+  // extract arguments from Arguments) in the right order.
+  Invoker(Arguments* args, int create_flags)
+      : ArgumentHolder<indices, ArgTypes>(args, create_flags)...,
+        args_(args) {}
 
-    Invoker<R, P1, P2>::Go(&args, holder->callback, a1, a2);
+  bool IsOK() {
+    return And(ArgumentHolder<indices, ArgTypes>::ok...);
   }
-};
-
-template<typename R, typename P1, typename P2, typename P3>
-struct Dispatcher<R(P1, P2, P3)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
 
-    typedef CallbackHolder<R(P1, P2, P3)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3>::Go(&args, holder->callback, a1, a2, a3);
+  template <typename ReturnType>
+  void DispatchToCallback(base::Callback<ReturnType(ArgTypes...)> callback) {
+    args_->Return(callback.Run(ArgumentHolder<indices, ArgTypes>::value...));
   }
-};
 
-template<typename R, typename P1, typename P2, typename P3, typename P4>
-struct Dispatcher<R(P1, P2, P3, P4)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2, P3, P4)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    typename CallbackParamTraits<P4>::LocalType a4;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3) ||
-        !GetNextArgument(&args, holder->flags, false, &a4)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3, P4>::Go(&args, holder->callback, a1, a2, a3, a4);
+  // In C++, you can declare the function foo(void), but you can't pass a void
+  // expression to foo. As a result, we must specialize the case of Callbacks
+  // that have the void return type.
+  void DispatchToCallback(base::Callback<void(ArgTypes...)> callback) {
+    callback.Run(ArgumentHolder<indices, ArgTypes>::value...);
   }
-};
 
-template<typename R, typename P1, typename P2, typename P3, typename P4,
-    typename P5>
-struct Dispatcher<R(P1, P2, P3, P4, P5)> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R(P1, P2, P3, P4, P5)> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    typename CallbackParamTraits<P4>::LocalType a4;
-    typename CallbackParamTraits<P5>::LocalType a5;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3) ||
-        !GetNextArgument(&args, holder->flags, false, &a4) ||
-        !GetNextArgument(&args, holder->flags, false, &a5)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3, P4, P5>::Go(&args, holder->callback, a1, a2, a3, a4,
-        a5);
+ private:
+  static bool And() { return true; }
+  template <typename... T>
+  static bool And(bool arg1, T... args) {
+    return arg1 && And(args...);
   }
+
+  Arguments* args_;
 };
 
-template<typename R, typename P1, typename P2, typename P3, typename P4,
-    typename P5, typename P6>
-struct Dispatcher<R(P1, P2, P3, P4, P5, P6)> {
+// DispatchToCallback converts all the JavaScript arguments to C++ types and
+// invokes the base::Callback.
+template <typename Sig>
+struct Dispatcher {};
+
+template <typename ReturnType, typename... ArgTypes>
+struct Dispatcher<ReturnType(ArgTypes...)> {
   static void DispatchToCallback(
       const v8::FunctionCallbackInfo<v8::Value>& info) {
     Arguments args(info);
@@ -456,27 +194,13 @@ struct Dispatcher<R(P1, P2, P3, P4, P5, P6)> {
     CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
         v8_holder->Value());
 
-    typedef CallbackHolder<R(P1, P2, P3, P4, P5, P6)> HolderT;
+    typedef CallbackHolder<ReturnType(ArgTypes...)> HolderT;
     HolderT* holder = static_cast<HolderT*>(holder_base);
 
-    typename CallbackParamTraits<P1>::LocalType a1;
-    typename CallbackParamTraits<P2>::LocalType a2;
-    typename CallbackParamTraits<P3>::LocalType a3;
-    typename CallbackParamTraits<P4>::LocalType a4;
-    typename CallbackParamTraits<P5>::LocalType a5;
-    typename CallbackParamTraits<P6>::LocalType a6;
-    if (!GetNextArgument(&args, holder->flags, true, &a1) ||
-        !GetNextArgument(&args, holder->flags, false, &a2) ||
-        !GetNextArgument(&args, holder->flags, false, &a3) ||
-        !GetNextArgument(&args, holder->flags, false, &a4) ||
-        !GetNextArgument(&args, holder->flags, false, &a5) ||
-        !GetNextArgument(&args, holder->flags, false, &a6)) {
-      args.ThrowError();
-      return;
-    }
-
-    Invoker<R, P1, P2, P3, P4, P5, P6>::Go(&args, holder->callback, a1, a2, a3,
-        a4, a5, a6);
+    using Indices = typename IndicesGenerator<sizeof...(ArgTypes)>::type;
+    Invoker<Indices, ArgTypes...> invoker(&args, holder->flags);
+    if (invoker.IsOK())
+      invoker.DispatchToCallback(holder->callback);
   }
 };
 
diff --git a/gin/function_template.h.pump b/gin/function_template.h.pump
deleted file mode 100644
index 20b2821..0000000
--- a/gin/function_template.h.pump
+++ /dev/null
@@ -1,240 +0,0 @@
-$$ This is a pump file for generating file templates.  Pump is a python
-$$ script that is part of the Google Test suite of utilities.  Description
-$$ can be found here:
-$$
-$$ http://code.google.com/p/googletest/wiki/PumpManual
-$$
-
-#ifndef GIN_FUNCTION_TEMPLATE_H_
-#define GIN_FUNCTION_TEMPLATE_H_
-
-$var MAX_ARITY = 6
-
-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/callback.h"
-#include "base/logging.h"
-#include "gin/arguments.h"
-#include "gin/converter.h"
-#include "gin/gin_export.h"
-#include "v8/include/v8.h"
-
-namespace gin {
-
-class PerIsolateData;
-
-enum CreateFunctionTemplateFlags {
-  HolderIsFirstArgument = 1 << 0,
-};
-
-namespace internal {
-
-template<typename T>
-struct CallbackParamTraits {
-  typedef T LocalType;
-};
-template<typename T>
-struct CallbackParamTraits<const T&> {
-  typedef T LocalType;
-};
-template<typename T>
-struct CallbackParamTraits<const T*> {
-  typedef T* LocalType;
-};
-
-
-// CallbackHolder and CallbackHolderBase are used to pass a base::Callback from
-// CreateFunctionTemplate through v8 (via v8::FunctionTemplate) to
-// DispatchToCallback, where it is invoked.
-
-// This simple base class is used so that we can share a single object template
-// among every CallbackHolder instance.
-class GIN_EXPORT CallbackHolderBase {
- public:
-  v8::Handle<v8::External> GetHandle(v8::Isolate* isolate);
-
- protected:
-  explicit CallbackHolderBase(v8::Isolate* isolate);
-  virtual ~CallbackHolderBase();
-
- private:
-  static void WeakCallback(
-      const v8::WeakCallbackData<v8::External, CallbackHolderBase>& data);
-
-  v8::Persistent<v8::External> v8_ref_;
-
-  DISALLOW_COPY_AND_ASSIGN(CallbackHolderBase);
-};
-
-template<typename Sig>
-class CallbackHolder : public CallbackHolderBase {
- public:
-  CallbackHolder(v8::Isolate* isolate,
-                 const base::Callback<Sig>& callback,
-                 int flags)
-      : CallbackHolderBase(isolate), callback(callback), flags(flags) {}
-  base::Callback<Sig> callback;
-  int flags;
- private:
-  virtual ~CallbackHolder() {}
-
-  DISALLOW_COPY_AND_ASSIGN(CallbackHolder);
-};
-
-
-// This set of templates invokes a base::Callback, converts the return type to a
-// JavaScript value, and returns that value to script via the provided
-// gin::Arguments object.
-//
-// In C++, you can declare the function foo(void), but you can't pass a void
-// expression to foo. As a result, we must specialize the case of Callbacks that
-// have the void return type.
-
-$range ARITY 0..MAX_ARITY
-$for ARITY [[
-$var INV_ARITY = MAX_ARITY - ARITY
-$range ARG 1..INV_ARITY
-$range VOID INV_ARITY+1..MAX_ARITY
-
-$if ARITY == 0 [[
-template<typename R$for ARG [[, typename P$(ARG) = void]]>
-struct Invoker {
-]] $else [[
-template<typename R$for ARG [[, typename P$(ARG)]]>
-struct Invoker<R$for ARG [[, P$(ARG)]]$for VOID [[, void]]> {
-]]
-
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<R($for ARG , [[P$(ARG)]])>& callback$for ARG [[, 
-      const P$(ARG)& a$(ARG)]]) {
-    args->Return(callback.Run($for ARG, [[a$(ARG)]]));
-  }
-};
-template<$for ARG , [[typename P$(ARG)]]>
-struct Invoker<void$for ARG [[, P$(ARG)]]$for VOID [[, void]]> {
-  inline static void Go(
-      Arguments* args,
-      const base::Callback<void($for ARG , [[P$(ARG)]])>& callback$for ARG [[,
-      const P$(ARG)& a$(ARG)]]) {
-    callback.Run($for ARG, [[a$(ARG)]]);
-  }
-};
-
-
-]]
-
-template<typename T>
-bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
-                     T* result) {
-  if (is_first && (create_flags & HolderIsFirstArgument) != 0) {
-    return args->GetHolder(result);
-  } else {
-    return args->GetNext(result);
-  }
-}
-
-// For advanced use cases, we allow callers to request the unparsed Arguments
-// object and poke around in it directly.
-inline bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
-                            Arguments* result) {
-  *result = *args;
-  return true;
-}
-inline bool GetNextArgument(Arguments* args, int create_flags, bool is_first,
-                            Arguments** result) {
-  *result = args;
-  return true;
-}
-
-// It's common for clients to just need the isolate, so we make that easy.
-inline bool GetNextArgument(Arguments* args, int create_flags,
-                            bool is_first, v8::Isolate** result) {
-  *result = args->isolate();
-  return true;
-}
-
-
-// DispatchToCallback converts all the JavaScript arguments to C++ types and
-// invokes the base::Callback.
-template<typename Sig>
-struct Dispatcher {
-};
-
-$range ARITY 0..MAX_ARITY
-$for ARITY [[
-$range ARG 1..ARITY
-
-template<typename R$for ARG [[, typename P$(ARG)]]>
-struct Dispatcher<R($for ARG , [[P$(ARG)]])> {
-  static void DispatchToCallback(
-      const v8::FunctionCallbackInfo<v8::Value>& info) {
-    Arguments args(info);
-    v8::Handle<v8::External> v8_holder;
-    CHECK(args.GetData(&v8_holder));
-    CallbackHolderBase* holder_base = reinterpret_cast<CallbackHolderBase*>(
-        v8_holder->Value());
-
-    typedef CallbackHolder<R($for ARG , [[P$(ARG)]])> HolderT;
-    HolderT* holder = static_cast<HolderT*>(holder_base);
-
-$if ARITY != 0 [[
-
-
-$for ARG [[    typename CallbackParamTraits<P$(ARG)>::LocalType a$(ARG);
-
-]]
-    if ($for ARG  ||
-        [[!GetNextArgument(&args, holder->flags, $if ARG == 1 [[true]] $else [[false]], &a$(ARG))]]) {
-      args.ThrowError();
-      return;
-    }
-
-]]
-
-    Invoker<R$for ARG [[, P$(ARG)]]>::Go(&args, holder->callback$for ARG [[, a$(ARG)]]);
-  }
-};
-
-]]
-
-}  // namespace internal
-
-
-// CreateFunctionTemplate creates a v8::FunctionTemplate that will create
-// JavaScript functions that execute a provided C++ function or base::Callback.
-// JavaScript arguments are automatically converted via gin::Converter, as is
-// the return value of the C++ function, if any.
-template<typename Sig>
-v8::Local<v8::FunctionTemplate> CreateFunctionTemplate(
-    v8::Isolate* isolate, const base::Callback<Sig> callback,
-    int callback_flags = 0) {
-  typedef internal::CallbackHolder<Sig> HolderT;
-  HolderT* holder = new HolderT(isolate, callback, callback_flags);
-
-  return v8::FunctionTemplate::New(
-      isolate,
-      &internal::Dispatcher<Sig>::DispatchToCallback,
-      ConvertToV8<v8::Handle<v8::External> >(isolate,
-                                             holder->GetHandle(isolate)));
-}
-
-// CreateFunctionHandler installs a CallAsFunction handler on the given
-// object template that forwards to a provided C++ function or base::Callback.
-template<typename Sig>
-void CreateFunctionHandler(v8::Isolate* isolate,
-                           v8::Local<v8::ObjectTemplate> tmpl,
-                           const base::Callback<Sig> callback,
-                           int callback_flags = 0) {
-  typedef internal::CallbackHolder<Sig> HolderT;
-  HolderT* holder = new HolderT(isolate, callback, callback_flags);
-  tmpl->SetCallAsFunctionHandler(&internal::Dispatcher<Sig>::DispatchToCallback,
-                                 ConvertToV8<v8::Handle<v8::External> >(
-                                     isolate, holder->GetHandle(isolate)));
-}
-
-}  // namespace gin
-
-#endif  // GIN_FUNCTION_TEMPLATE_H_
diff --git a/gin/wrappable_unittest.cc b/gin/wrappable_unittest.cc
index 8dbaf30..ef0dce4 100644
--- a/gin/wrappable_unittest.cc
+++ b/gin/wrappable_unittest.cc
@@ -94,11 +94,11 @@ class MyCallableObject : public Wrappable<MyCallableObject> {
 
   ~MyCallableObject() override {}
 
-  void Call(int val, const gin::Arguments& arguments) {
+  void Call(int val1, int val2, int val3, const gin::Arguments& arguments) {
     if (arguments.IsConstructCall())
       arguments.ThrowTypeError("Cannot be called as constructor.");
     else
-      result_ = val;
+      result_ = val1;
   }
 
   int result_;
@@ -230,7 +230,7 @@ TEST_F(WrappableTest, CallAsFunction) {
   EXPECT_EQ(0, object->result());
   v8::Handle<v8::String> source = StringToV8(isolate,
                                              "(function(obj) {"
-                                             "obj(42);"
+                                             "obj(42, 2, 5);"
                                              "})");
   gin::TryCatch try_catch;
   v8::Handle<v8::Script> script = v8::Script::Compile(source);
@@ -253,7 +253,7 @@ TEST_F(WrappableTest, CallAsConstructor) {
   EXPECT_EQ(0, object->result());
   v8::Handle<v8::String> source = StringToV8(isolate,
                                              "(function(obj) {"
-                                             "new obj(42);"
+                                             "new obj(42, 2, 5);"
                                              "})");
   gin::TryCatch try_catch;
   v8::Handle<v8::Script> script = v8::Script::Compile(source);