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:

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 // 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:

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 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:

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 function WDDX(xmldoc) {

    var data = xmldoc.getElementsByTagName("data")[0];

    this.content = new WDDXNode(

        data.getFirstElementChild(),

        this

    );

    this.setting = null;

}

and:

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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.

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