getting property of a wrapper object

[Dormilich]

Hi,

I’m doing XML deserialization and I want the properties of a wrapper object accessible to all subobjects, that are created inside it.

first some code to show how it works:

// some stuff left out
function WDDX(xmldoc)
{
    var data = xmldoc.getElementsByTagName("data")[0];
    this.content = new WDDXNode(data.getFirstElementChild());
    this.setting = null;
}
 
WDDX.prototype.deserialize = function()
{
    return this.content.parse();
}
 
function WDDXNode(knoten)
{
    this.node = knoten;
    this.name = knoten.tagName.toLowerCase();
    this.text = knoten.firstChild.data;
    this.elements = knoten.getElementChildren();
}
 
WDDXNode.prototype.parse = function()
{
    switch (this.name) {
        case "array"   : return this.getArray();
        case "boolean" : return this.getBoolean();
        // and some more
    }
}
 
// a method where new objects are created
WDDXNode.prototype.getStruct = function()
{
    var JSObject, StructIndex, items;
    var type = String(this.node.getAttribute("type"));
    if (setting == "whatever value")
        // do some additional stuff like getting the classname from elsewhere
    if (type && "function" == typeof window[type])
        JSObject = new window[type];
    else
        JSObject = new Object;
 
    items = this.node.getElementChildren("var");
    for (var l, i = 0, l = items.length; i < l; i++) { 
        var item = new WDDXNode(items[i].getFirstElementChild());
        StructIndex = items[i].getAttribute("name");
        JSObject[StructIndex] = item.parse();
    }
    return JSObject;
}

the usage is quite plain:

var x = new WDDX(XMLHttpRequest.responseXML);
x.setting = "whatever value";
var deser = x.deserialize();

the setting property is a value, that should be used in some of the WDDXNode methods, but I don’t have an idea, how to pass it around. I thought of the Observer Pattern, but I can’t pass around the WDDX object as Subject (if I do that, I could read the value directly…) and I don’t want to use a global, since it would affect all active WDDX instances. so has anyone an idea how to do that?

thanks, Dormi

[gits]

why not passing the 'parent'-obj reference to the child-constructor like:

function WDDX(xmldoc) {
    var data = xmldoc.getElementsByTagName("data")[0];
    this.content = new WDDXNode(
        data.getFirstElementChild(),
        this
    );
    this.setting = null;
}

and:

function WDDXNode(knoten, parent) {
    this.node = knoten;
    this.name = knoten.tagName.toLowerCase();
    this.text = knoten.firstChild.data;
    this.elements = knoten.getElementChildren();
 
    this.parentSetting = function() {
        return parent.setting;
    }
}
 

kind regards

[Dormilich]

I hoped, I could do without passing the wrapper object… and I probably don’t need the closure since the WDDXNode cascade will be started only by parsing the first node.

[gits]

while you don't need the closure (it was just an example :) ) i think without passing the reference it would get quite complicated to get the reference then? you could even try to use a setter for the 'setting' property that passes something (or notify) the child node when the property is changing.

kind regards

[Dormilich]

I guess I’ll use a global, because I don’t consider the effort worth the gain.