准备开始
首先我们用下面的目录结构来创建一个节点通知(node-notify)文件夹.
.
|– build/ # This is where our extension is built.
|– demo/
| `– demo.js # This is a demo Node.js script to test our extension.
|– src/
| `– node_gtknotify.cpp # This is the where we do the mapping from C++ to Javascript.
`– wscript # This is our build configuration used by node-waf
这个看起来很漂亮的tree 用通用的 tree 生成.
现在让我来创建测试脚本demo.js 和决定我们扩展的API前期看起来应该像:
// This loads our extension on the notify variable.
// It will only load a constructor function, notify.notification().
var notify = require("../build/default/gtknotify.node"); // path to our extensionvar notification = new notify.notification();
notification.title = "Notification title";
notification.icon = "emblem-default"; // see /usr/share/icons/gnome/16x16
notification.send("Notification message");
编写我们的Node.js扩展
Init方法
为了创建一个Node.js扩展，我们需要编写一个继承node::ObjectWrap的C++类。 ObjectWrap 实现了让我们更容易与Javascript交互的公共方法
我们先来编写类的基本框架：
#include <v8.h> // v8 is the Javascript engine used by QNode
#include <node.h>
// We will need the following libraries for our GTK+ notification
#include <string>
#include <gtkmm.h>
#include <libnotifymm.h>using namespace v8;
class Gtknotify : node::ObjectWrap {
private:
public:
Gtknotify() {}
~Gtknotify() {}
static void Init(Handle<Object> target) {
// This is what Node will call when we load the extension through require(), see boilerplate code below.
}
};
/*
* WARNING: Boilerplate code ahead.
*
* See https://www.cloudkick.com/blog/2010/aug/23/writing-nodejs-native-extensions/ & http://www.freebsd.org/cgi/man.cgi?query=dlsym
*
* Thats it for actual interfacing with v8, finally we need to let Node.js know how to dynamically load our code.
* Because a Node.js extension can be loaded at runtime from a shared object, we need a symbol that the dlsym function can find,
* so we do the following:
*/
v8::Persistent<FunctionTemplate> Gtknotify::persistent_function_template;
extern "C" { // Cause of name mangling in C++, we use extern C here
