backbone.js的类继承骨干代码qwrap实现

var Model = function(opt){
    this._config(opt);
    this.init.apply(this,arguments);
}
QW.ObjectH.mix(Model.prototype,{
    init : function(){},
    _config : function(opt){
        var opt = opt||{};
        QW.ObjectH.mix(this,opt,true);
    },
    attrs : {},
    get : function(key){
        if (this.attr.hasOwnProperty(key)) {
            return this.attr[key];
        }
        return null;
    },
    set : function(key,val,override){
        if(override){
            this.attr[key] = val;
        }else{
            if (!this.attr.hasOwnProperty(key)) {
                this.attr[key] = val;
            }
        }
    }
});


var extend = function(proto, props){
    var child = inherits(this, proto, props);
    child.extend = this.extend;
    return child;
};
var inherits = function(p,proto, props){
    var child;
    if (proto && proto.hasOwnProperty('constructor')) {
        child = proto.constructor;
    } else {
        child = function(){ p.apply(this, arguments); };
    }
    function ctor(){};
    ctor.prototype = p.prototype;
    
    child.prototype = new ctor;
    child.prototype.constructor = child;
    
    if(proto){
        QW.ObjectH.mix(child.prototype,proto,true);
    }
    if(props){
        QW.ObjectH.mix(child,props,true);
    }
    child.__super__ = p.prototype;
    return child;
};
Model.extend = extend;
var app = {};
app.model = Model.extend({
    init : function(){
        alert(1);
    }
});
app.model2 = app.model.extend({
    init : function(){
        alert(2);
    }
});
var _app = new app.model2({test:'test'});