[英]Implementing inheritance in node.js bindings
I am writing Node.js bindings around a C++ library. 我正在围绕C ++库编写Node.js绑定。 I can identify key objects in the C++ library that I can expose as classes to the Node.js (ie derivatives of ObjectWrap).
我可以识别C ++库中的关键对象,我可以将它作为类暴露给Node.js(即ObjectWrap的衍生物)。 I can also see an inheritance relationship between these objects.
我还可以看到这些对象之间的继承关系。
How can I expose ClassA
, ClassB
, ClassC
as node.js classes (derivatives of ObjectWrap
) and manipulate their prototypes (in v8 C++ code) so that ClassB
and ClassC
are derivates of ClassA
? 我如何将
ClassA
, ClassB
, ClassC
为node.js类( ObjectWrap
衍生物)并操纵它们的原型(在v8 C ++代码中),以便ClassB
和ClassC
是ClassA
派生?
This can be done using v8::FunctionTemplate
's Inherit
method. 这可以使用
v8::FunctionTemplate
的Inherit
方法完成。 It's explained here . 它在这里解释。 Here's a working example.
这是一个有效的例子。
C++ code: C ++代码:
#include <v8.h>
#include <node.h>
using namespace node;
using namespace v8;
class BaseClass : ObjectWrap
{
public:
static Persistent<FunctionTemplate> s_ct;
static void Init(v8::Handle<Object> target)
{
Local<FunctionTemplate> t = FunctionTemplate::New(New);
s_ct = Persistent<FunctionTemplate>::New(t);
s_ct->InstanceTemplate()->SetInternalFieldCount(1);
s_ct->SetClassName(String::NewSymbol("BaseClass"));
NODE_SET_PROTOTYPE_METHOD(s_ct, "getName", getName);
target->Set(String::NewSymbol("BaseClass"), s_ct->GetFunction());
}
BaseClass(){}
~BaseClass(){}
static v8::Handle<Value> New(const Arguments& args)
{
HandleScope scope;
return args.This();
}
static v8::Handle<Value> getName(const Arguments& args)
{
HandleScope scope;
return scope.Close(String::New("Base"));
}
};
Persistent<FunctionTemplate> BaseClass::s_ct;
class DerivedClass : ObjectWrap
{
public:
static Persistent<FunctionTemplate> s_ct;
static void Init(v8::Handle<Object> target)
{
Local<FunctionTemplate> t = FunctionTemplate::New(New);
s_ct = Persistent<FunctionTemplate>::New(t);
// XXX Inherit from BaseClass
s_ct->Inherit(BaseClass::s_ct);
s_ct->InstanceTemplate()->SetInternalFieldCount(1);
s_ct->SetClassName(String::NewSymbol("DerivedClass"));
NODE_SET_PROTOTYPE_METHOD(s_ct, "getAge", getAge);
target->Set(String::NewSymbol("DerivedClass"), s_ct->GetFunction());
}
DerivedClass() {}
~DerivedClass() {}
static v8::Handle<Value> New(const Arguments& args) {
HandleScope scope;
return args.This();
}
static v8::Handle<Value> getAge(const Arguments& args)
{
HandleScope scope;
return scope.Close(Number::New(42));
}
};
Persistent<FunctionTemplate> DerivedClass::s_ct;
extern "C" {
static void init (v8::Handle<Object> target)
{
BaseClass::Init(target);
DerivedClass::Init(target);
}
NODE_MODULE(mymodule, init);
}
Put it in standard node-gyp
configuration and you can test it with following javascript 将它放在标准的
node-gyp
配置中,您可以使用以下javascript进行测试
var mymodule = require('./build/Release/mymodule');
var baseObject = new mymodule.BaseClass();
var dervObject = new mymodule.DerivedClass();
console.log(baseObject.getName());
console.log(dervObject.getName(), dervObject.getAge());
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