CODEWITHSUNDEEP
javascriptc++node.jsv8
Silviu-Marian
Silviu-Marian

Reputation: 10927

Javascript equivalents in V8?

I'm playing with NodeJS and V8 in an attempt to learn both.

I'd like to translate this simple JS line in C++.

global.Game = { sleep: call_some_CPP_function };

For the past two days, I've been piecing together code found on the Internet and in other people's source code, trying to understand how it works, except I didn't end up with much.

The code below doesn't work, if I do a console.log(global.Game), I get nothing.

#include "node.h"
#include "v8.h"

namespace node{

    using namespace v8; // make life easier

    // define a sleepy thread blocker
    Handle<Value> call_some_CPP_function(const FunctionCallbackInfo<Value>& a){
        HandleScope scope(node_isolate);
        Sleep(3);
        return scope.Close(Undefined());
    }

    // let's create the object here
    // I'm calling this function elsewhere 
    void execme(){

        // I've read somewhere that I have to do this
        Locker locker(node_isolate);
        HandleScope scope(node_isolate);

        // I think these two set the execution context (variables) and "this" accordingly 
        // but I'm not sure
        Local<Context> context = node_isolate->GetCurrentContext();
        Context::Scope context_scope(context);

        // I need a reference to the global object, to assign my "Game" object
        Local<Object> global = node_env->context()->Global();

        // The only way is to invent a constructor for it
        Local<FunctionTemplate> function_template = FunctionTemplate::New();
        function_template->SetClassName(String::New("GameClass"));

        // and create a new instance using that constructor
        Local<Object> game_object = function_template->GetFunction()->NewInstance();

        // after that, add the "sleep" function, which executes the function above
        NODE_SET_METHOD(game_object, "sleep", call_some_CPP_function); 

        // and finally do the global.Game assignment
        global->Set(String::New("Game"), game_object);
    }

}

Upvotes: 2

Views: 397

Answers (2)

MiMFa
MiMFa

Reputation: 1174

I think it's a good function to sleep, because it works on the other platforms which based JS.

function sleep(milliseconds) {
  const date = Date.now();
  let currentDate = null;
  do {
    currentDate = Date.now();
  } while (currentDate - date < milliseconds);
}

Upvotes: 0

damphat
damphat

Reputation: 18966

game.cc

#include <node.h>
#include <v8.h>

using namespace v8;

// sleep 3 seconds
Handle<Value> Sleep(const Arguments& args) {
  HandleScope scope;
  Sleep(3000);
  return scope.Close(Undefined());
}

void init(Handle<Object> exports) {
  exports->Set(String::NewSymbol("sleep"),
      FunctionTemplate::New(Sleep)->GetFunction());
}

NODE_MODULE(game, init)

app.js

global.Game = require('./build/Release/game');

console.log(global.Game); // this will print "{ sleep: [Function] }"

//now you can call native sleep
Game.sleep();

Document: http://nodejs.org/api/addons.html#addons_hello_world

Upvotes: 2

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