Question

I have several very similar functions:

v8::Handle<v8::Value> jsAudioPlay(const v8::Arguments &args) {
    Audio *audio = static_cast<Audio*>(args.This()->GetPointerFromInternalField(0));
    if (audio != NULL) audio->play(get(args[0], 0));
    return args.This();
}

v8::Handle<v8::Value> jsAudioPause(const v8::Arguments &args) {
    Audio *audio = static_cast<Audio*>(args.This()->GetPointerFromInternalField(0));
    if (audio != NULL) audio->pause();
    return args.This();
}

v8::Handle<v8::Value> jsAudioLoop(const v8::Arguments &args) {
    Audio *audio = static_cast<Audio*>(args.This()->GetPointerFromInternalField(0));
    if (audio != NULL) audio->loop(get(args[0], -1));
    return args.This();
}

v8::Handle<v8::Value> jsAudioVolume(const v8::Arguments &args) {
    Audio *audio = static_cast<Audio*>(args.This()->GetPointerFromInternalField(0));
    if (audio != NULL) audio->volume(get(args[0], 1.0f));
    return args.This();
}

And I’ve been reading about C++ templates for hours and I’m convinced that it’s possible to get rid of these functions and replace them with templates. I envision the end result will be something like:

typedef Handle<Value> (*InvocationCallback)(const Arguments& args);

template <class T> InvocationCallback FunctionWrapper ...;
template <class T> FunctionWrapper FunctionReal ...;
template <class T, class arg1> FunctionWrapper FunctionReal ...;
template <class T, class arg1, class arg2> FunctionWrapper FunctionReal ...;

I realize similar questions have been asked, but I can’t find an example of a template within a template like the above.

---

Update on 7/21/2012

Template:

template <class T> v8::Handle<v8::Value> jsFunctionTemplate(const v8::Arguments &args) {
    T *t = static_cast<T*>(args.This()->GetPointerFromInternalField(0));
    if (t != NULL) t->volume(args[0]->NumberValue());
    return args.This();
}

Usage:

audio->PrototypeTemplate()->Set("Volume", v8::FunctionTemplate::New(&jsFunctionTemplate<Audio>));

Now if I could only figure out how to pass &Audio::volume to the template, I’ll be in business.

---

Update on 7/24/2012

Refer to my answer for how I solved this.

Answer 1

My Templates:

template <class T, class RT, RT(T::*f)()> v8::Handle<v8::Value> jsFunctionTemplate(const v8::Arguments &args) {
    T *t = static_cast<T*>(args.This()->GetPointerFromInternalField(0));
    if (t != NULL) (t->*f)();
    return args.This();
}
template <class T, class RT, class A0, RT(T::*f)(A0)> v8::Handle<v8::Value> jsFunctionTemplate(const v8::Arguments &args) {
    T *t = static_cast<T*>(args.This()->GetPointerFromInternalField(0));
    if (t != NULL) (t->*f)(jsConvert<A0>(args[0]));
    return args.This();
}
template <class T, class RT, class A0, class A1, RT(T::*f)(A0, A1)> v8::Handle<v8::Value> jsFunctionTemplate(const v8::Arguments &args) {
    T *t = static_cast<T*>(args.This()->GetPointerFromInternalField(0));
    if (t != NULL) (t->*f)(jsConvert<A0>(args[0]), jsConvert<A1>(args[1]));
    return args.This();
}

Usage:

audio->PrototypeTemplate()->Set("Play", v8::FunctionTemplate::New(&jsFunctionTemplate<Audio, Audio*, int, &Audio::play>));
audio->PrototypeTemplate()->Set("Pause", v8::FunctionTemplate::New(&jsFunctionTemplate<Audio, Audio*, &Audio::pause>));
audio->PrototypeTemplate()->Set("Loop", v8::FunctionTemplate::New(&jsFunctionTemplate<Audio, Audio*, int, &Audio::loop>));
audio->PrototypeTemplate()->Set("Volume", v8::FunctionTemplate::New(&jsFunctionTemplate<Audio, Audio*, float, &Audio::volume>));

Now I need to figure out the two final steps: variable number of arguments, and properly templating jsConvert to return the desired type <A0>.